وزن

در زبان علمی و مهندسی، به نیرویی که در اثر گرانش به یک جسم وارد می‌شود، وزن می‌گویند.[۱][۲] ولی امروزه همهٔ مردم و حتی در بسیاری از متن‌های رسمی و قانونی در جایی از واژهٔ وزن استفاده می‌کنند که منظور جرم جسم است.

در گذشته بزرگی یک نیرو را با W (به صورت ایرانیک) نمایش می‌دادیم. بزرگی نیرو عبارت است از جرم جسم یا m ضرب در بزرگی شتاب محلی گرانش زمین[۳] یا g پس می‌توان گفت: W = mg. در فضای بردای وزن را با نماد W (به صورت پُررنگ) نمایش می‌دهیم. یکای اندازه‌گیری وزن در سامانهٔ استاندارد بین‌المللی یکاها یا SI نیوتن در نظر گرفته شده‌است. برای نمونه جسمی با جرم ۱ کیلوگرم وزنی برابر با ۹٫۸ نیوتن، در سطح زمین دارد و در سطح ماه وزنی برابر با حدود یک-ششم (۱/۶) وزن خود در زمین دارد و در فضایی دور از جرم‌های آسمانی به گونه‌ای که اثر نیروی گرانش آن‌ها بر جسم نزدیک صفر باشد، می‌توان گفت که جسم تقریبا بی‌وزن است.

محتویات [نمایش]
پیشینه [ویرایش]

گذشتهٔ مفهوم سنگینی و سبکی به تاریخ فلسفهٔ یونان باستان باز می‌گردد. مفهوم‌های سبکی و سنگینی در دید آن‌ها به عنوان ویژگی‌های ذاتی ماده در نظر گرفته می‌شد. افلاطون وزن را به صورت تمایل طبیعی ماده به بازگشت به خویش توصیف کرده بود. در دید ارسطو، سبکی و سنگینی نشان دهندهٔ تمایل به حفظ نظم طبیعی چهار عنصر پایه‌ای جهان: هوا، خاک، آب و آتش است. او سنگینی مطلق را به خاک و سبکی مطلق را به آتش نسبت داد. ارشمیدوس وزن را به عنوان ویژگیی در برابر شناوری دانست و آن را در کشمکش میان غرق شدن یا شناور ماندن یک جسم بر روی سیال موثر دانست. اولین تعریف ریاضی وزن از سوی اقلیدوس گفته شد؛ وی تعریف کرد که: «وزن، سنگینی یا سبکی یک جسم نسبت به دیگری است که با ترازو اندازه‌گیری می‌شود.»[۲]

نسبت وزن روی زمین با سایر سیاره‌ها و ماه [ویرایش]

تیر ۰٫۳۷۸
ناهید ۰٫۹۰۷
زمین ۱
ماه ۰٫۱۶۵
بهرام ۰٫۳۷۷
مشتری ۲٫۳۶۴
کیوان ۰٫۹۱۰
اورانوس ۰٫۸۸۹
نپتون ۱٫۱۲۵
یادداشت و منبع [ویرایش]

مشارکت‌کنندگان ویکی‌پدیا، «Weight»، ویکی‌پدیای انگلیسی، دانشنامهٔ آزاد (بازیابی در ‏۲۴ سپتامبر ۲۰۱۱).

↑ Richard C. Morrison (1999). "Weight and gravity - the need for consistent definitions". The Physics Teacher 37: 51. Bibcode 1999PhTea..۳۷...۵۱M. DOI:10.1119/1.880152.
↑ ۲٫۰ ۲٫۱ Igal Galili (2001). "Weight versus gravitational force: historical and educational perspectives". International Journal of Science Education 23: 1073. Bibcode 2001IJSEd..۲۳٫۱۰۷۳G. DOI:10.1080/09500690110038585.
↑ Gat, Uri (1988). "The weight of mass and the mess of weight". In Richard Alan Strehlow. Standardization of Technical Terminology: Principles and Practice – second volume. ای‌اس‌تی‌ام بین‌الملل. pp. 45–۴۸. ISBN 978-0-8031-1183-7. http://books.google.com/books?id=CoB5w9Km0mUC&pg=PA45.
پیوند به بیرون [ویرایش]

پرواز در بی‌وزنی



این یک نوشتار خُرد پیرامون فیزیک است. با گسترش آن به ویکی‌پدیا کمک کنید.
در ویکی‌انبار پرونده‌هایی دربارهٔ وزن موجود است.
رده‌های صفحه: بازرگانی جرم (فیزیک)فیزیولوژی نیرو

قس ترکی آذری

Çəki — cismin dayağa və ya asqıya göstərdiyi təsir qüvvəsi. Ədədi qiymətcə çismin ağırlıq qüvvəsinə bərabərdir: P=mg (m — cismin kütləsi, g — sərbəstdüşmə təcilidir). Cismin çəkisi qütblərdə ən böyük, ekvatorda isə ən kiçikdir, qütblərdən ekvatora getdikcə və Yer səthindən uzaqlaşdıqca cismin çəkisi azalır. Cəki dayağa və ya asqıya təsir edən qüvvə olduğündan onu yaylı tərəzi (dinamometr) vasitəsilə ölçmək olar. Çəki N, kQ və s. qüvvə vahidləri ilə ölçülür.
Cisim şaquli yuxarı yönəlmiş a təcili ilə hərəkət edərsə onun çəkisi artar və P=m(g+a) olar.
Əlavə yüklənmə – cismin çəkisinin onun ağırlıq qüvvəsinə olan nisbətinə deyilir, n=P\mg=m(g+a)\mg=1+a\g. Məsələn, kosmik uçuşa start götürdükdə kosmanavtlar əlavə yüklənməyə məruz qalırlar. Cisim aşağı yönəlmiş a təcili ilə hərəkət etdikdə isə çəki P=m(g-a) düsturu ilə hesablanar və azalar. Əgər g=a olarsa P=0 olar.
Çəkisizlik – cismin çəkisinin sıfıra bərabər olan halına deyilir. Məsələn, sərbəst düşən liftdəki cisimlər, Yer ətrafında fırlana peykin içindəki cisimlər və kosmanavt çəkisizlik halında olur. Ağırlıq qüvvəsi cismin təcillə hərəkət etməsindən və ya sükunətdə olmasından asılı deyil, cismin kütlə mərkəzinə tətbiq olunur və Yerin mərkəzinə doğru yönəlir. Cismin çəkisi asqıya və dayağa tətbiq olunur, dayağa perpendikulyardır.
[redaktə]Ədəbiyyat

M.Murquzov.Fizika.VIII sinif üçün dərslik.
Kateqoriya: Qüvvə

قس ترکی استانبولی

Ağırlık, bir cisme uygulanan kütle çekim kuvvetidir. Dünya'da bir cismi ele alırsak yükseğe çıkıldıkça ağırlığı azalır, kutuplara gidildikçe ağırlığı artar, ekvatora gittikçe ağırlığı azalır. Ağırlık birimi newton'dur ve kısaca 'N' ile gösterilir.
Yatay bir taban üzerine konan bir cismin, o taban üzerine yaptığı basınca ya da bir noktaya asılı bir cismin, o noktaya uyguladığı yer çekimi kuvvetine verilen ad.
Bu bakımdan, ağırlığın yönü, yer çekimi kuvvetinin yönündedir. Bu da, cismin kütlesine ve o yerin ivmesine bağlıdır. İvme, yeryüzünde cismin bulunduğu yere göre değişebildiğine göre, kütlesi sabit olan bir cismin mutlak ağırlığı, küre üzerinde bulunduğu yere göre değişebilir.
Ağırlık Merkezi:
Bir cismin parçacıkları üzerine etki eden yerçekimleri bileşkesinin uygulama noktasına verilen ad. Boşluğa bırakılan her cisim, yerçekiminin etkisi altında kalarak düşer. Yerçekimi, cismin yere düşmesini, dolayısıyla bir ağırlığı olmasını sağlar. Yerçekimi kuvveti, kütlesi (m) olan bir nokta gibi tasarlanan cismin parçacıklarına ayrı ayrı etki yapar. Bir cismin ağırlık merkezi, o cismin meydana gelmesini sağlayan noktalar sisteminin, o noktada toplanmış ve yerçekimi kuvveti o noktaya etki ediyormuş gibi olan halidir. Bir cismin ağırlık merkezinin de. neyle elde edilmesi, onun şekline göre değişir.
Ağırlık merkezinin bilinmesi ,cisimlerin denge hallerini ve çeşitli yapıtların devrilmeden durabilmelerinin sağlanmasında yardımcı olur.
Ağırlık=Kütle x Yer çekimi ivmesi
Kütlesi 1 kg olan bir cisim
Güneş'te 247.2 N
Merkür'de 3.71 N
Venüs'te 8.87 N
Dünya'da 9.81 N
Ay'da 1.62 N(Ay'daki ağırlık Dünya'daki ağırlığın 6'da 1'idir.)
Mars'ta 3.77 N
Jüpiter'de 23.30 N(ağırlık dinanometre ile ölçülür)
Satürn'de 9.2 N
Uranüs'de 8.69 N
Neptün'de 11 N
Plüton'da 0.06 N'dur.
1 kg'lık kütlenin ağırlığı Paris'te 9,81 N. alınırsa
Ekvator'da 9,78 N
Kutuplarda 9,83 N
İstanbul'da 9,80 N
Ankara'da 9,78 N
Antalya'da 9,76 N ölçülür.
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Kategori: Fizik taslakları

قس عبری

משקל (באנגלית: Weight) הוא כוח הכבידה שמפעיל כדור הארץ או גרם שמים אחר על עצם שנמצא בסמוך אליו. במערכת MKS, משקל נמדד ביחידות ניוטון. כיוון שהוא סוג של כוח, לפעמים מודדים משקל גם בקילוגרם-כוח (קג"כ).
בשפת היום-יום משתמשים במילה משקל לציון שני מושגים נוספים. האחד הוא מסה שאיננה מהווה כוח אלא תכונה של העצם. במילה משקל משתמשים גם לציון "המשקל הנדמה" (apparent weight), שהוא הכוח שמפעילה תמיכה על העצם. כך למשל, הכוח שמפעילה עלינו הקרקע, ואותו אנו חשים, הוא המשקל הנדמה.
תוכן עניינים [הצגה]
[עריכה]משקל ומסה

מסה היא תכונה פנימית של הגוף, ואינה תלויה במערכת הייחוס (להוציא אפקטים יחסותיים). מסה נמדדת בקילוגרמים. משקל, לעומת זאת, מתאר את הכוח הפועל על גוף, והוא משתנה בהתאם לגרם השמים שמושך את העצם. כך למשל, משקל של גוף על הירח יהיה קטן יותר מאשר משקלו על כדור הארץ.
הבדל חשוב נוסף הוא כי המסה היא סקלר, והמשקל הוא וקטור. כלומר, המסה אינה פועלת בכיוון מסוים, שכן אין משמעות לטענה שהמסה היא 50 ק"ג בכיוון ימין, לדוגמה. המשקל הוא גודל ווקטורי, והוא פועל בכיוון אחד. על כן המסה תישמר גם בתנאים של חוסר כבידה, בחלל למשל.
בחיי היומיום, לרוב משתמשים במלה משקל במשמעות של מסה, וזאת כי אנו משתמשים במכשיר הקרוי "משקל" כדי למדוד מסה. כשאנו קונים תפוחים, לדוגמה, אנו מודדים את מסת התפוחים בעזרת מכשיר המודד את הכוח שהתפוחים מפעילים על משטח או על קפיץ תלוי. מדידה זו אינה מודדת את מסת התפוחים, אלא את משקלם. כיוון שבין המשקל למסה יש יחס ישר, ניתן להסיק ממדידת המשקל את המסה. יש לשים לב שבמדידה זו אנו מסתמכים על כך שתאוצת הכובד שווה בקירוב טוב בכל מקום על פני כדור הארץ. לכן, המשקל של שקית תפוחים לא תלוי במיקום שבו היא מתבצעת.
[עריכה]משקל נדמה

לתאוצה של מערכת הייחוס יש השפעה על המשקל הנדמה, אך לא על המשקל הרגיל ולא על המסה. במעלית המאיצה כלפי מעלה אנו מרגישים משקל גדול יותר, כלומר המשקל הנדמה גדול יותר. אולם, מסת גופנו והמשקל שלו לא משתנים. חשוב לציין כי זו אינה רק "תחושה" - אם נעמוד על משקל הוא אכן ימדוד משקל נדמה גדול יותר בזמן שהמעלית מאיצה כלפי מעלה. למעשה, אין דרך ניסיונית להבחין בין הימצאות במעלית מאיצה לבין הימצאות בשדה כבידה. זהו אחד מהעקרונות המרכזיים בתורת היחסות הכללית של איינשטיין.
המשקל הנדמה הוא הכוח שמפעילה תמיכה על גוף, כך שלא יפול בנפילה חופשית. חשוב לשים לב כי כאשר אומרים שהגוף לא נופל, מגדירים למעשה מערכת ייחוס שיחסית אליה הגוף לא נע. נבחן ניסוי בו שוקלים את שקית התפוחים במעלית המאיצה כלפי מעלה, על ידי הנחה על משקל אלקטרוני, לדוגמה. המשקל מודד את הכוח הנורמלי שהוא מפעיל על השקית. במערכת המעלית, השקית אכן לא נמצאת בתאוצה, והכוח הנורמלי שפועל עליה הוא , כאשר היא תאוצת המעלית. כיוון שהכוח שנורמלי שהמשקל מפעיל גדל, נובע כי המשקל, כפי שהוגדר, משתנה. חשוב לזכור כי למדען המבצע את הניסוי במעלית אין כלל יכולת לדעת שהוא במערכת מאיצה. ואכן, אם הוא לא יכייל את הקפיץ מחדש, הוא יטעה בחישוב מסת התפוחים.
[עריכה]"חוסר משקל"



במערכת החללית, האסטרנאוטים מרגישים חסרי משקל
אסטרונאוטים הנמצאים במסלול לווייני סביב כדור הארץ מרגישים "חוסר משקל", כלומר המשקל הנדמה שלהם הוא 0. האסטרונאוטים, יחד עם החללית, מקיפים את כדור הארץ במסלול מעגלי ולכן ניתן להבין שפועל עליהם כוח כבידה, אולם הם נמצאים בנפילה חופשית יחסית לכדור הארץ ולכן לא פועל עליהם כוח, אף על פי שיש להם מסה.
אם נכליל את המקרים שבחנו - האסטרנאוטים במסלול והתפוחים במעלית - נוכל לומר באופן הכללי ביותר, שמשקלו של גוף הנמצא במנוחה במערכת מסוימת, שווה למסתו מוכפלת בתאוצת הנפילה החופשית במערכת. לתאוצת נפילה החופשית יחסית למערכת קוראים שדה הכבידה האפקטיבי או בקיצור g האפקטיבי. יחסית לחללית, g האפקטיבי הוא אפס (כי אם משחררים גוף, הוא לא מאיץ כלל יחסית לחללית), ולכן משקלם של האסטרונאוטים הוא אפס. במעלית מאיצה כלפי מעלה, g האפקטיבי גדול יותר מברחבת השוק, ולכן התפוחים ישקלו יותר במעלית מאשר בשוק.
חשוב להבין כי כאשר גוף מונח על משטח או תלוי על חוט, הכוח המחזיק אותו (הכוח הנורמלי או המתיחות) וכוח הכובד אינם בהכרח צמד פעולה-תגובה.
[עריכה]השתנות המשקל על פני כדור הארץ

שדה הכבידה על פני כדור הארץ אינו אחיד ממש, אלא רק בקירוב. השוני בין מקומות שונים נובע מכך שכדור הארץ אינו עגול אלא פחוס, וכן מאפקטים של הכוח הצנטריפוגלי הנובע מסיבוב כדור הארץ סביב צירו. תאוצת הכובד הממוצעת על פני כדור הארץ היא בסביבות 9.8m/s², אך היא משתנה בטווח של עשיריות האחוז.
תאוצת הכובד במקומות שונים על כדור הארץ (m/s²)
אמסטרדם 9.813 גלזגו 9.816 פריז 9.809
אתונה 9.807 הוואנה 9.788 ריו דה ז'ניירו 9.788
אוקלנד 9.799 הלסינקי 9.819 רומא 9.803
בנגקוק 9.783 כווית 9.793 סן פרנסיסקו 9.800
בריסל 9.811 ליסבון 9.801 סינגפור 9.781
בואנוס איירס 9.797 לונדון 9.812 סטוקהולם 9.818
כלכותה 9.788 לוס אנג'לס 9.796 סידני 9.797
קייפ טאון 9.796 מדריד 9.800 טאיפיי 9.790
שיקגו 9.803 מנילה 9.784 טוקיו 9.798
קופנהגן 9.815 מקסיקו סיטי 9.779 ונקובר 9.809
ניקוסיה 9.797 ניו יורק 9.802 וושינגטון 9.801
ג'קרטה 9.781 אוסלו 9.819 ולינגטון 9.803
פרנקפורט 9.810 אוטווה 9.806 ציריך 9.807
מכאן נובע, לדוגמה, כי משקלה של שקית תפוחים בשוק של ציריך יהיה גדול ב 0.24% ממשקל אותה שקית בבנגקוק.
[עריכה]ראו גם

כוח (פיזיקה)
כבידה
תאוצה
קטגוריות: כוחות פיזיקלייםכבידה

قس روسی

Вес — сила воздействия тела на опору (или подвес или другой вид крепления), препятствующую падению, возникающая в поле сил тяжести[1]. (В случае нескольких опор под весом понимается суммарная сила, действующая на все опоры; впрочем, для жидких и газообразных опор в случае погружения тела в них часто делается исключение, т. е. тогда силы воздействия тела на них исключают из веса и включают в силу Архимеда). Единица измерения веса в СИ — ньютон, иногда используется единица СГС — дина.
Вес P тела, покоящегося в инерциальной системе отсчёта , совпадает с силой тяжести, действующей на тело, и пропорционален массе и ускорению свободного падения в данной точке:

Значение веса (при неизменной массе тела) пропорционально ускорению свободного падения, которое зависит от высоты над земной поверхностью (или поверхностью другой планеты, если тело находится вблизи нее, а не Земли, и массы и размеров этой планеты), и, ввиду несферичности Земли, а также ввиду ее вращения (см. ниже), от географических координат точки измерения. Другим фактором, влияющим на ускорение свободного падения и, соответственно, вес тела, являются гравитационные аномалии, обусловленные особенностями строения земной поверхности и недр в окрестностях точки измерения.
При движении системы тело — опора (или подвес) относительно инерциальной системы отсчёта c ускорением вес перестаёт совпадать с силой тяжести:

В результате суточного вращения Земли существует широтное уменьшение веса: на экваторе примерно на 0,3 % меньше, чем на полюсах.


Широтное уменьшение веса.
Вес можно измерять с помощью пружинных весов, которые могут служить и для косвенного измерения массы, если их соответствующим образом проградуировать; рычажные весы в такой градуировке не нуждаются, так как в этом случае сравниваются массы, на которые действует одинаковое ускорение свободного падения или сумма ускорений в неинерциальных системах отсчёта. При взвешивании с помощью технических пружинных весов вариациями ускорения свободного падения обычно пренебрегают, так как влияние этих вариаций обычно меньше практически необходимой точности взвешивания.
На вес тела в жидкой или газообразной среде влияет также сила Архимеда, таким образом, вес тела, погружённого в среду, уменьшается на вес вытесненного объёма среды; в случае, если плотность тела меньше плотности среды, вес становится отрицательным (то есть на тело действует выталкивающая сила). Сила Архимеда может оказать влияние и на взвешивание с помощью рычажных весов, если сравниваются тела с различной плотностью.
Состояние отсутствия веса (невесомость) наступает при удалении тела от притягивающего объекта, либо когда тело находится в свободном падении, то есть .
[править]Вес и масса

В современной науке вес и масса — разные понятия. Вес — сила, с которой тело действует на горизонтальную опору или вертикальный подвес. Масса же не является силовым фактором; масса — мера инертности тела. Например, в условиях невесомости у всех тел вес равен нулю, а масса у каждого тела своя. И если в состоянии покоя тела показания весов будут нулевыми, то при ударе по весам тел с одинаковыми скоростями воздействие будет разным (см. закон сохранения импульса, закон сохранения энергии).
Вместе с тем строгое различение понятий веса и массы принято в основном в физике, а во многих повседневных ситуациях слово «вес» продолжает использоваться, когда фактически речь идет о «массе». Например, мы говорим, что какой-то объект «весит один килограмм», несмотря на то, что килограмм представляет собой единицу массы. Кроме того, термин «вес» в значении «масса» традиционно используется в цикле наук о человеке — в сочетании «вес тела человека»[2][3][4].
[править]Примечания

↑ «Вес». // Физическая энциклопедия. Гл. ред. Прохоров А. М. — М.: «Советская энциклопедия», 1988. — Т. 1. — С. 262. — 704 с.
↑ Медицинская энциклопедия на Академике
↑ Григорьева, Ольга Валентиновна — Работоспособность студентов-спортсменов, специализирующихся в единоборствах, при регуляции массы тела с использованием пищевых биологически активных добавок — диссертация на соискание ученой степени кандидата педагогических наук : 13.00.04 Москва, 2003 145 c.
↑ Ростовцев Владимир Леонидович — Биологическое обоснование технологии применения внетренировочных средств для повышения работоспособности спортсменов высокой квалификации — диссертация на соискание ученой степени доктора биологических наук, МОСКВА — 2008
[править]См. также

В Викисловаре есть статья «вес»
Масса
Геоид
Гравиметрия
Фигура Земли
Весы
Силы, действующие на самолёт[скрыть]
Подъёмная сила • Вес • Тяга • Лобовое сопротивление

Категория: Сила

قس اسپانیائی

En física clásica, el peso es la fuerza con la cual un cuerpo actúa sobre un punto de apoyo, y que está originada por la acción del campo gravitatorio local sobre la masa del cuerpo. Por ser una fuerza, el peso se representa como un vector, definido por su módulo, dirección y sentido, aplicado en el centro de gravedad del cuerpo y dirigido aproximadamente hacia el centro de la Tierra. Por extensión de esta definición, también podemos referirnos al peso de un cuerpo en cualquier otro astro (Luna, Marte,...) en cuyas proximidades se encuentre.
Los conceptos newtonianos de la gravedad fueron desafiados por la relatividad en el siglo 20. El principio de equivalencia de Einstein coloca todos los observadores en el mismo plano. Esto condujo a una ambigüedad en cuanto a qué es exactamente lo que se entiende por la "fuerza de la gravedad" y, en consecuencia, peso. Las ambigüedades introducidas por la relatividad condujeron, a partir de la década de 1960, a un considerable debate en la comunidad educativa sobre cómo definir el peso a sus alumnos. La elección fue una definición newtoniana de peso como la fuerza de un objeto en reposo en el suelo debido a la gravedad, o una definición operacional definida por el acto de pesaje.[cita requerida] En la definición operacional, el peso se convierte en cero, en condiciones de ingravidez como en la órbita de la Tierra o la caída libre en el vacío. En tales situaciones, la visión newtoniana es que sigue existiendo una fuerza debido a la gravedad que no se mide (causando así un peso aparente de cero), mientras que la vista einsteiniana es que nunca existe una fuerza medible debido a la gravedad (incluso en el suelo ), sino que, en caída libre, ninguna fuerza puede medirse debido a que el suelo no ejerce la fuerza mecánica que ordinariamente se observó como "peso".
La magnitud del peso de un objeto, desde la definición operacional de peso, depende tan sólo de la intensidad del campo gravitatorio local y de la masa del cuerpo, en un sentido estricto. Sin embargo, desde un punto de vista legal y práctico, se establece que el peso, cuando el sistema de referencia es la Tierra, comprende no solo la fuerza gravitatoria local, sino también la fuerza centrífuga local debido a la rotación de la Tierra; por el contrario, el empuje atmosférico no se incluye, ni ninguna otra fuerza externa.1
Contenido [ocultar]
1 Peso y masa
2 Unidades de peso
3 Cálculo del peso
4 Comparación del peso en el sistema solar
5 El peso de un ser humano
6 Sensación de peso
7 Véase también
8 Referencias
8.1 Bibliografía
9 Enlaces externos
[editar]Peso y masa



El dinamómetro sirve para medir el peso de los cuerpos.
Peso y masa son dos conceptos y magnitudes físicas bien diferenciadas, aunque aún en estos momentos, en el habla cotidiana, el término "peso" se utiliza a menudo erróneamente como sinónimo de masa, la cual es una magnitud escalar. La propia Academia reconoce esta confusión en la definición de «pesar»: "Determinar el peso, o más propiamente, la masa de algo por medio de la balanza o de otro instrumento equivalente".2
La masa de un cuerpo es una propiedad intrínseca del mismo, la cantidad de materia, independiente de la intensidad del campo gravitatorio y de cualquier otro efecto. Representa la inercia o resistencia del cuerpo a los cambios de estado de movimiento (aceleración, masa inercial), además de hacerla sensible a los efectos de los campos gravitatorios (masa gravitatoria).
El peso de un cuerpo, en cambio, no es una propiedad intrínseca del mismo, ya que depende de la intensidad del campo gravitatorio en el lugar del espacio ocupado por el cuerpo. La distinción científica entre "masa" y "peso" no es importante para muchos efectos prácticos porque la fuerza gravitatoria no experimenta grandes cambios en las proximidades de la superficie terrestre. En un campo gravitatorio constante la fuerza que ejerce la gravedad sobre un cuerpo (su peso) es directamente proporcional a su masa. Pero en realidad el campo gravitatorio terrestre no es constante; puede llegar a variar hasta en un 0,5% entre los distintos lugares de la Tierra, lo que significa que se altera la relación "masa-peso" con la variación de la fuerza de la gravedad.
Por el contrario, el peso de un mismo cuerpo experimenta cambios muy significativos al cambiar el objeto masivo que crea el campo gravitatorio. Así, por ejemplo, una persona de 60 kg (6,118 UTM) de masa, pesa 588,34 N (60 kgf) en la superficie de la Tierra. La misma persona, en la superficie de la Luna pesaría tan sólo unos 98,05 N (10 kgf); sin embargo, su masa seguirá siendo de 60 kg (6,118 UTM). Nota: En cursiva, Sistema Internacional; (entre paréntesis), Sistema Técnico de Unidades.
Bajo la denominación de peso aparente se incluyen otros efectos, además de la fuerza gravitatoria y el efecto centrífugo, como la flotación, el carácter no inercial del sistema de referencia (v.g., un ascensor acelerado), etc. El peso que mide el dinamómetro, es en realidad el peso aparente; el peso real sería el que mediría en el vacío en un referencial inercial.
[editar]Unidades de peso

Como el peso es una fuerza, se mide en unidades de fuerza. Sin embargo, las unidades de peso y masa tienen una larga historia compartida, en parte porque su diferencia no fue bien entendida cuando dichas unidades comenzaron a utilizarse.
Sistema Internacional de Unidades
Este sistema es el prioritario o único legal en la mayor parte de las naciones (excluidas Birmania y Estados Unidos), por lo que en las publicaciones científicas, en los proyectos técnicos, en las especificaciones de máquinas, etc., las magnitudes físicas se expresan en unidades del sistema internacional de unidades (SI). Así, el peso se expresa en unidades de fuerza del SI, esto es, en newtons (N):
1 N = 1 kg · 1 m/s²
Sistema Técnico de Unidades
En el Sistema Técnico de Unidades, el peso se mide en kilogramo-fuerza (kgf) o kilopondio (kp), definido como la fuerza ejercida sobre un kilogramo de masa por la aceleración en caída libre (g = 9,80665 m/s²)3
1 kp = 9,80665 N = 9,80665 kg·m/s²
Otros sistemas
También se suele indicar el peso en unidades de fuerza de otros sistemas, como la dina, la libra-fuerza, la onza-fuerza, etcétera.
La dina es la unidad CGS de fuerza y no forma parte del SI. Algunas unidades inglesas, como la libra, pueden ser de fuerza o de masa. Las unidades relacionadas, como el slug, forman parte de sub-sistemas de unidades.
[editar]Cálculo del peso



Contribución de las aceleraciones gravitatoria y centrífuga en el peso.
El cálculo del peso de un cuerpo a partir de su masa se puede expresar mediante la segunda ley de la dinámica:

donde el valor de es la aceleración de la gravedad (ver) en el lugar en el que se encuentra el cuerpo. En primera aproximación, si consideramos a la Tierra como una esfera homogénea, se puede expresar con la siguiente fórmula:

de acuerdo a la ley de gravitación universal.
En realidad, el valor de la aceleración de la gravedad en la Tierra, a nivel del mar, varía entre 9,789 m/s2 en el ecuador y 9,832 m/s2 en los polos. Se fijó convencionalmente en 9,80665 m/s2 en la tercera Conferencia General de Pesos y Medidas convocada en 1901 por la Oficina Internacional de Pesos y Medidas (Bureau International des Poids et Mesures).4 Como consecuencia, el peso varía en la misma proporción.
[editar]Comparación del peso en el sistema solar



Anomalías del campo gravitacional terrestre (expresado en miligal5 ) respecto del valor estimado, considerando la variación del radio terrestre.
La siguiente lista describe el peso de un cuerpo de «masa unidad» en la superficie de algunos cuerpos del sistema solar, comparándolo con su peso en la Tierra:
Cuerpo celeste Peso relativo g (m/s2)
Sol 27,90 274,1
Mercurio 0,377 3,703
Venus 0,907 8,872
Tierra 1 9,82266
Luna 0,165 1,625
Marte 0,377 3,728
Júpiter 2,364 25,93
Saturno 0,921 9,05
Urano 0,889 9,01
Neptuno 1,125 11,28
[editar]El peso de un ser humano

Artículo principal: Obesidad.


Correlación entre la masa (kg) y la altura (cm) de un ser humano.
Por término medio, un recién nacido tiene una masa de 3 a 4 kilogramos (coloquialmente se dice que pesa de 3 a 4 kilos), y a los doce meses tiene una masa de 9 a 12 kilogramos.
El índice de masa corporal establece la relación entre la masa y la talla de la persona. La ecuación para calcular el IMC es: masa corporal ("peso", expresada en kilogramos) dividida entre el cuadrado de la estatura (expresada en metros).
IMC de 18,5-24,9 se considera un peso saludable.
IMC de 25,0-29,9 se considera sobrepeso.
IMC de 30,0-39,9 se considera obesidad.
IMC de 40,0 o más se considera obesidad severa u obesidad mórbida).
Se han dado casos extremos en los que la diferencia entre el peso de una persona y el peso promedio llegaba a exceder cientos de kilogramos. Hasta la fecha, Jon Brower Minnoch es la persona que más ha pesado de la que se tienen datos, mientras que la persona viva más pesada es Manuel Uribe Garza.
[editar]Sensación de peso

La sensación de peso se debe a la fuerza ejercida por los fluidos del sistema vestibular, un juego de tres dimensiones de las cavidades del oído interno. En realidad, la sensación de "Fuerza G", independientemente de ser estacionaria la presencia de la gravedad, o, si el cuerpo está en movimiento, el resultado de otras fuerzas que actúan sobre el mismo, como en el caso de la aceleración o desaceleración de un ascensor, o la fuerza que sentimos al montar en una montaña rusa.
[editar]Véase también

Intensidad del campo gravitatorio
Newton (unidad)
Gal (unidad)
Peso molecular
Peso atómico
Gravedad
[editar]Referencias

↑ ISO 80000-4:2006. Quantities and units, part 4, Mechanics, item 4-9.2, «weight» (International System of Quantities).
↑ «pesar», Diccionario de la lengua española (vigésima segunda edición), Real Academia Española, 2001.
↑ ISO 80000-3:2006. Quantities and units, part 3, Space and time, item 3-9.2, «acceleration of free fall» (International System of Quantities).
↑ El valor de g se ha definido como un promedio de valor nominal, que representa la aceleración de un cuerpo en caída libre a nivel del mar en la latitud geodésica de 45,5°.
↑ 1 miligal = 10-5 m/s2.
↑ Este valor difiere del convencional: 9,806 ya que no se tiene en cuenta la aceleración centrífuga: 65 m/s²
[editar]Bibliografía
Ortega, Manuel R. (1989-2006) (en español). Lecciones de física (4 volúmenes). Monytex. ISBN 84-404-4290-4, ISBN 84-398-9218-7, ISBN 84-398-9219-5, ISBN 84-604-4445-7.
Resnick,Robert & Krane, Kenneth S. (2001) (en inglés). Physics. New York: John Wiley & Sons. ISBN 0-471-32057-9.
Tipler, Paul A. (2000) (en español). Física para la ciencia y la tecnología (2 volúmenes). Barcelona: Ed. Reverté. ISBN 84-291-4382-3.
[editar]Enlaces externos

Wikimedia Commons alberga contenido multimedia sobre Peso.
Wikcionario tiene definiciones para Peso.
Wikiquote alberga frases célebres de o sobre Peso.
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Categorías: FuerzaMagnitudes físicasMasa

قس انگلیسی

In science and engineering, the weight of an object is the force on the object due to gravity.[1][2] Its magnitude (a scalar quantity), often denoted by an italic letter W, is the product of the mass m of the object and the magnitude of the local gravitational acceleration g;[3] thus: W = mg. When considered a vector, weight is often denoted by a bold letter W. The unit of measurement for weight is that of force, which in the International System of Units (SI) is the newton. For example, an object with a mass of one kilogram has a weight of about 9.8 newtons on the surface of the Earth, about one-sixth as much on the Moon, and very nearly zero when in deep space far away from all bodies imparting gravitational influence.
In the 20th century, the Newtonian concepts of gravitation were challenged by relativity. Einstein's principle of equivalence put all observers, accelerating in space far from gravitating bodies, or held in place against gravitation near such a body, on the same footing. This led to an ambiguity as to what exactly is meant by the "force of gravity" and (in consequence) by weight. The ambiguities introduced by relativity led, starting in the 1960s, to considerable debate in the teaching community as how to define weight for their students. The choice was a Newtonian definition of weight as the contact reaction-force against the force of gravity, for an object at rest on the ground, or an operational definition defined by the act of weighing.[2] In the operational definition, weight becomes zero in conditions of weightlessness such as Earth orbit or free fall in vacuum. In such situations, the Newtonian view is that there remains a force due to gravity which is not measured (thus causing an apparent weight of zero), while the Einsteinian view is that there never does exist a measurable force due to gravity, even in everyday experience. Instead, weight and all sensation of weight are always produced by contact forces (push or pull) from the ground, or a scale. In free-fall, no force is measured simply because the force due to gravity is (still) never felt, and the floor (or the scale) now fails to exert the mechanical force that is what is always observed as "weight."
In everyday usage the term "weight" is commonly used to mean mass, which scientifically is an entirely different concept.[4] On the surface of the Earth, the acceleration due to gravity (the "strength of gravity") is approximately constant; this means that the ratio of the weight force of a motionless object on the surface of the Earth to its mass is almost independent of its location, so that an object's weight force can stand as a proxy for its mass, and vice versa.
Contents [show]
[edit]History



Weighing grain, from the Babur-namah
Discussion of the concepts of heaviness (weight) and lightness (levity) date back to the ancient Greek philosophers. These were typically viewed as inherent properties of objects. Plato described weight as the natural tendency of objects to seek their kin. To Aristotle weight and levity represented the tendency to restore the natural order of the basic elements: air, earth, fire and water. He ascribed absolute weight to earth and absolute levity to fire. Archimedes saw weight as a quality opposed to buoyancy, with the conflict between the two determining if an object sinks or floats. The first operational definition of weight was given by Euclid, who defined weight as: "weight is the heaviness or lightness of one thing, compared to another, as measured by a balance."[2]
According to Aristotle, weight was the direct cause of the falling motion of an object, the speed of the falling object was supposed to be directly proportionate to the weight of the object. As medieval scholars discovered that in practice the speed of a falling object increased with time, this prompted a change to the concept of weight to maintain this cause effect relationship. Weight was split into a "still weight" or pondus, which remained constant, and the actual gravity or gravitas, which changed as the object fell. The concept of gravitas was eventually replaced by Jean Buridan's impetus, a precursor to momentum.[2]
The rise of the Copernican view of the world led to the resurgence of the Platonic idea that like objects attract but in the context of heavenly bodies. In the 17th century, Galileo made significant advances in the concept of weight. He proposed a way to measure the difference between the weight of a moving object and an object at rest. Ultimately, he concluded weight was proportionate to the amount of matter of an object, and not the speed of motion as supposed by the Aristotelean view of physics.[2]
[edit]Newton
The introduction of Newton's laws of motion and the development of Newton's law of universal gravitation led to considerable further development of the concept of weight. Weight became fundamentally separate from mass. Mass was identified as a fundamental property of objects connected to their inertia, while weight became identified with the force of gravity on an object and therefore dependent on the context of the object. In particular, Newton considered weight to be relative to another object causing the gravitational pull, e.g. the weight of the Earth towards the Sun.[2]
Newton considered time and space to be absolute. This allowed him to consider concepts as true position and true velocity.[clarification needed] Newton also recognized that weight as measured by the action of weighing was affected by environmental factors such as buoyancy. He considered this a false weight induced by imperfect measurement conditions, for which he introduced the term apparent weight as compared to the true weight defined by gravity.[2]
Although Newtonian physics made a clear distinction between weight and mass, the term weight continued to be commonly used when people meant mass. This led the 3rd General Conference on Weights and Measures (CGPM) of 1901 to officially declare "The word weight denotes a quantity of the same nature as a force: the weight of a body is the product of its mass and the acceleration due to gravity", thus distinguishing it from mass for official usage.
[edit]Relativity
In the 20th century, the Newtonian concepts of absolute time and space were challenged by relativity. Einstein's principle of equivalence put all observers, moving or accelerating, on the same footing. This led to an ambiguity as to what exactly is meant by the force of gravity and weight. A scale in an accelerating elevator cannot be distinguished from a scale in a gravitational field. Gravitational force and weight thereby became essentially frame-dependent quantities. This prompted the abandonment of the concept as superfluous in the fundamental sciences such as physics and chemistry. Nonetheless, the concept remained important in the teaching of physics. The ambiguities introduced by relativity led, starting in the 1960s, to considerable debate in the teaching community as how to define weight for their students, choosing between a nominal definition of weight as the force due to gravity or an operational definition defined by the act of weighing.[2]
[edit]Definitions



This top-fuel dragster can accelerate from zero to 160 kilometres per hour (99 mph) in 0.86 seconds. This is a horizontal acceleration of 5.3 g. Combined with the vertical g-force in the stationary case the Pythagorean theorem yields a g-force of 5.4 g. It is this gravitional-force that causes the driver's weight if one uses the operational definition. If one uses the gravitational definition, the driver's weight is unchanged by the motion of the car.
Several definitions exist for weight, not all of which are equivalent.[3][5][6][7]
[edit]Gravitational definition
The most common definition of weight found in introductory physics textbooks defines weight as the force exerted on a body by gravity.[1][7] This is often expressed in the formula W = mg, where W is the weight, m the mass of the object, and g gravitational acceleration.
In 1901, the 3rd General Conference on Weights and Measures (CGPM) established this as their official definition of weight:
"The word weight denotes a quantity of the same nature[Note 1] as a force: the weight of a body is the product of its mass and the acceleration due to gravity."

— Resolution 2 of the 3rd General Conference on Weights and Measures[9][10]

This resolution defines weight as a vector, since force is a vector quantity. However, some textbooks also take weight to be a scalar by defining:
"The weight W of a body is equal to the magnitude Fg of the gravitational force on the body."[11]

The gravitational acceleration varies from place to place. Sometimes, it is simply taken to a have a standard value of 9.80665 m/s2, which gives the standard weight.[9]
The force whose magnitude is equal to mg newtons is also known as the m kilogram weight (which term is abbreviated to kg-wt)[12]
Measuring weight versus mass



Left: A spring scale measures weight, by seeing how much the object pushes on a spring (inside the device). On the Moon, an object would give a lower reading. Right: A balance scale measures mass, by comparing an object to references. On the Moon, an object would give the same reading, because the object and references would both become lighter.
[edit]Operational definition
In the operational definition, the weight of an object is the force measured by the operation of weighing it, which is the force it exerts on its support.[5] This can make a considerable difference, depending on the details; for example, an object in free fall exerts little if any force on its support, a situation that is commonly referred to as weightlessness. However, being in free fall does not affect the weight according to the gravitational definition. Therefore, the operational definition is sometimes refined by requiring that the object be at rest.[citation needed] However, this raises the issue of defining "at rest" (usually being at rest with respect to the Earth is implied by using standard gravity[citation needed]). In the operational definition, the weight of an object at rest on the surface of the Earth is lessened by the effect of the centrifugal force from the Earth's rotation.
The operational definition, as usually given, does not explicitly exclude the effects of buoyancy, which reduces the measured weight of an object when it is immersed in a fluid such as air or water. As a result, a floating balloon or an object floating in water might be said to have zero weight.
[edit]ISO definition
In the ISO International standard ISO 80000-4(2006),[13] describing the basic physical quantities and units in mechanics as a part of the International standard ISO/IEC 80000, the definition of weight is given as:
Definition

,
where m is mass and g is local acceleration of free fall.
Remarks
It should be noted that, when the reference frame is Earth, this quantity comprises not only the local gravitational force, but also the local centrifugal force due to the rotation of the Earth, a force which varies with latitude.
The effect of atmospheric buoyancy is excluded in the weight.
In common parlance, the name "weight" continues to be used where "mass" is meant, but this practice is deprecated.
— ISO 80000-4 (2006)

The definition is dependent on the chosen frame of reference. When the chosen frame is co-moving with the object in question then this definition precisely agrees with the operational definition.[6] If the specified frame is the surface of the Earth, the weight according to the ISO and gravitational definitions differ only by the centrifugal effects due to the rotation of the Earth.
[edit]Apparent weight
Main article: Apparent weight
In many real world situations the act of weighing may produce a result that differs from the ideal value provided by the definition used. This is usually referred to as the apparent weight of the object. A common example of this is the effect of buoyancy, when an object is immersed in a fluid the displacement of the fluid will cause an upward force on the object, making it appear lighter when weighed on a scale.[14] The apparent weight may be similarly affected by levitation and mechanical suspension. When the gravitational definition of weight is used, the operational weight measured by an accelerating scale is often also referred to as the apparent weight.[15]
[edit]Weight and mass



A force diagram showing the forces acting on an object at rest on a surface. Notice that the amount of force that the table is pushing upward on the object (the N vector) is equal to the downward force of the object's weight (shown here as mg, as weight is equal to the object's mass multiplied with the acceleration due to gravity): because these forces are equal, the object is in a state of equilibrium (all the forces acting on it balance to zero).
Main article: Mass versus weight
In modern scientific usage, weight and mass are fundamentally different quantities: mass is an "extrinsic" (extensive) property of matter, whereas weight is a force that results from the action of gravity on matter: it measures how strongly the force of gravity pulls on that matter. However, in most practical everyday situations the word "weight" is used when, strictly, "mass" is meant.[4][16] For example, most people would say that an object "weighs one kilogram", even though the kilogram is a unit of mass.
The scientific distinction between mass and weight is unimportant for many practical purposes because the strength of gravity is almost the same everywhere on the surface of the Earth. In a uniform gravitational field, the gravitational force exerted on an object (its weight) is directly proportional to its mass. For example, object A weighs 10 times as much as object B, so therefore the mass of object A is 10 times greater than that of object B. This means that an object's mass can be measured indirectly by its weight, and so, for everyday purposes, weighing (using a weighing scale) is an entirely acceptable way of measuring mass. Similarly, a balance measures mass indirectly by comparing the weight of the measured item to that of an object(s) of known mass. Since the measured item and the comparison mass are in virtually the same location, so experiencing the same gravitational field, the effect of varying gravity does not affect the comparison or the resulting measurement.
The Earth's gravitational field is not uniform but can vary by as much as 0.5%[17] at different locations on Earth (see Earth's gravity). These variations alter the relationship between weight and mass, and must be taken into account in high precision weight measurements that are intended to indirectly measure mass. Spring scales, which measure local weight, must be calibrated at the location at which the objects will be used to show this standard weight, to be legal for commerce.[citation needed]
This table shows the variation of acceleration due to gravity (and hence the variation of weight) at various locations on the Earth's surface.[18]
Location Latitude m/s2
Equator 0° 9.7803
Sydney 33°52′ S 9.7968
Aberdeen 57°9′ N 9.8168
North Pole 90° N 9.8322
The historic use of "weight" for "mass" also persists in some scientific terminology – for example, the chemical terms "atomic weight", "molecular weight", and "formula weight", can still be found rather than the preferred "atomic mass" etc.
In a different gravitational field, for example, on the surface of the Moon, an object can have a significantly different weight than on Earth. The gravity on the surface of the Moon is only about one-sixth as strong as on the surface of the Earth. A one-kilogram mass is still a one-kilogram mass (as mass is an extrinsic property of the object) but the downward force due to gravity, and therefore its weight, is only one-sixth of what the object would have on Earth. So a man of mass 180 pounds weighs only about 30 pounds-force when visiting the Moon.
[edit]SI units
In most modern scientific work, physical quantities are measured in SI units. The SI unit of weight is the same as that of force: the newton (N) – a derived unit which can also be expressed in SI base units as kg·m/s2 (kilograms times meters per second squared).[16]
In commercial and everyday use, the term "weight" is usually used to mean mass, and the verb "to weigh" means "to determine the mass of" or "to have a mass of". Used in this sense, the proper SI unit is the kilogram (kg).[16]
[edit]Pound and other non-SI units
In United States customary units, the pound can be either a unit of force or a unit of mass. Related units used in some distinct, separate subsystems of units include the poundal and the slug. The poundal is defined as the force necessary to accelerate an object of one-pound mass at 1 ft/s2, and is equivalent to about 1/32.2 of a pound-force. The slug is defined as the amount of mass that accelerates at 1 ft/s2 when one pound-force is exerted on it, and is equivalent to about 32.2 pounds (mass).
The kilogram-force is a non-SI unit of force, defined as the force exerted by a one kilogram mass in standard Earth gravity (equal to 9.80665 newtons exactly). The dyne is the cgs unit of force and is not a part of SI, while weights measured in the cgs unit of mass, the gram, remain a part of SI.
[edit]Sensation of weight

See also: Apparent weight
The sensation of weight is caused by the force exerted by fluids in the vestibular system, a three-dimensional set of tubes in the inner ear.[dubious – discuss] It is actually the sensation of g-force, regardless of whether this is due to being stationary in the presence of gravity, or, if the person is in motion, the result of any other forces acting on the body such as in the case of acceleration or deceleration of a lift, or centrifugal forces when turning sharply.
[edit]Measuring weight

Main article: Weighing scale


A weighbridge, used for weighing trucks
Weight is commonly measured using one of two methods. A spring scale or hydraulic or pneumatic scale measures local weight, the local force of gravity on the object (strictly apparent weight force). Since the local force of gravity can vary by up to 0.5% at different locations, spring scales will measure slightly different weights for the same object (the same mass) at different locations. To standardize weights, scales are always calibrated to read the weight an object would have at a nominal standard gravity of 9.80665 m/s2 (approx. 32.174 ft/s2). However, this calibration is done at the factory. When the scale is moved to another location on Earth, the force of gravity will be different, causing a slight error. So to be highly accurate, and legal for commerce, spring scales must be re-calibrated at the location at which they will be used.
A balance on the other hand, compares the weight of an unknown object in one scale pan to the weight of standard masses in the other, using a lever mechanism – a lever-balance. The standard masses are often referred to, non-technically, as "weights". Since any variations in gravity will act equally on the unknown and the known weights, a lever-balance will indicate the same value at any location on Earth. Therefore, balance "weights" are usually calibrated and marked in mass units, so the lever-balance measures mass by comparing the Earth's attraction on the unknown object and standard masses in the scale pans. In the absence of a gravitational field, away from planetary bodies (e.g. space), a lever-balance would not work, but on the Moon, for example, it would give the same reading as on Earth. Some balances can be marked in weight units, but since the weights are calibrated at the factory for standard gravity, the balance will measure standard weight, i.e. what the object would weigh at standard gravity, not the actual local force of gravity on the object.
If the actual force of gravity on the object is needed, this can be calculated by multiplying the mass measured by the balance by the acceleration due to gravity – either standard gravity (for everyday work) or the precise local gravity (for precision work). Tables of the gravitational acceleration at different locations can be found on the web.
Gross weight is a term that generally is found in commerce or trade applications, and refers to the total weight of a product and its packaging. Conversely, net weight refers to the weight of the product alone, discounting the weight of its container or packaging; and tare weight is the weight of the packaging alone.
[edit]Relative weights on the Earth and other celestial bodies

Main articles: Earth's gravity and Surface gravity
The table below shows comparative gravitational accelerations at the surface of the Sun, the Earth's moon, each of the planets in the solar system. The “surface” is taken to mean the cloud tops of the gas giants (Jupiter, Saturn, Uranus and Neptune). For the Sun, the surface is taken to mean the photosphere. The values in the table have not been de-rated for the centrifugal effect of planet rotation (and cloud-top wind speeds for the gas giants) and therefore, generally speaking, are similar to the actual gravity that would be experienced near the poles.
Body Multiple of
Earth gravity Surface gravity
m/s2
Sun 27.90 274.1
Mercury 0.3770 3.703
Venus 0.9032 8.872
Earth 1 (by definition) 9.8226[19]
Moon 0.1655 1.625
Mars 0.3895 3.728
Jupiter 2.640 25.93
Saturn 1.139 11.19
Uranus 0.917 9.01
Neptune 1.148 11.28
[edit]See also

Body weight
[edit]Notes

^ The phrase "quantity of the same nature" is a literal translation of the French phrase grandeur de la même nature. Although this is an authorized translation, VIM 3 of the International Bureau of Weights and Measures recommends translating grandeurs de même nature as quantities of the same kind.[8]
[edit]References

^ a b Richard C. Morrison (1999). "Weight and gravity - the need for consistent definitions". The Physics Teacher 37: 51. Bibcode 1999PhTea..37...51M. doi:10.1119/1.880152.
^ a b c d e f g h Igal Galili (2001). "Weight versus gravitational force: historical and educational perspectives". International Journal of Science Education 23: 1073. Bibcode 2001IJSEd..23.1073G. doi:10.1080/09500690110038585.
^ a b Gat, Uri (1988). "The weight of mass and the mess of weight". In Richard Alan Strehlow. Standardization of Technical Terminology: Principles and Practice – second volume. ASTM International. pp. 45–48. ISBN 978-0-8031-1183-7.
^ a b The National Standard of Canada, CAN/CSA-Z234.1-89 Canadian Metric Practice Guide, January 1989:
5.7.3 Considerable confusion exists in the use of the term "weight." In commercial and everyday use, the term "weight" nearly always means mass. In science and technology "weight" has primarily meant a force due to gravity. In scientific and technical work, the term "weight" should be replaced by the term "mass" or "force," depending on the application.
5.7.4 The use of the verb "to weigh" meaning "to determine the mass of," e.g., "I weighed this object and determined its mass to be 5 kg," is correct.
^ a b Allen L. King (1963). "Weight and weightlessness". American Journal of Physics 30: 387. Bibcode 1962AmJPh..30..387K. doi:10.1119/1.1942032.
^ a b A. P. French (1995). "On weightlessness". American Journal of Physics 63: 105–106. Bibcode 1995AmJPh..63..105F. doi:10.1119/1.17990.
^ a b Galili, I.; Lehavi, Y. (2003). "The importance of weightlessness and tides in teaching gravitation". American Journal of Physics 71 (11): 1127–1135. Bibcode 2003AmJPh..71.1127G. doi:10.1119/1.1607336.
^ Working Group 2 of the Joint Committee for Guides in Metrology (JCGM/WG 2) (2008) (in English and French). International vocabulary of metrology — Basic and general concepts and associated terms (VIM) — Vocabulaire international de métrologie — Concepts fondamentaux et généraux et termes associés (VIM) (JCGM 200:2008) (3rd ed.). BIPM. Note 3 to Section 1.2.
^ a b "Resolution of the 3rd meeting of the CGPM (1901)". BIPM.
^ Barry N. Taylor and Ambler Thompson, ed. (2008). The International System of Units (SI). NIST Special Publication 330 (2008 ed.). NIST. p. 52.
^ Halliday, David; Resnick, Robert; Walker, Jearl (2007). Fundamentals of Physics, Volume 1 (8th ed.). Wiley. p. 95. ISBN 978-0-470-04473-5.
^ Chester, W. Mechanics. George Allen & Unwin. London. 1979. ISBN 0-04-510059-4. Section 3.2 at page 83.
^ ISO 80000-4:2006, Quantities and units - Part 4: Mechanics
^ Bell, F. (1998). Principles of mechanics and biomechanics. Stanley Thornes Ltd. pp. 174–176. ISBN 978-0-7487-3332-3.
^ Galili, Igal (1993). "Weight and gravity: teachers’ ambiguity and students’ confusion about the concepts". International Journal of Science Education 15 (2): 149–162. Bibcode 1993IJSEd..15..149G. doi:10.1080/0950069930150204.
^ a b c A. Thompson and B. N. Taylor (July 2, 2009 (last updated: March 3, 2010)). "The NIST Guide for the use of the International System of Units, Section 8: Comments on Some Quantities and Their Units". Special Publication 811. NIST. Retrieved 2010-05-22.
^ Hodgeman, Charles, Ed. (1961). Handbook of Chemistry and Physics, 44th Ed.. Cleveland, USA: Chemical Rubber Publishing Co.. p.3480-3485
^ Clark, John B (1964). Physical and Mathematical Tables. Oliver and Boyd.
^ This value excludes the adjustment for centrifugal force due to Earth’s rotation and is therefore greater than the 9.80665 m/s2 value of standard gravity.
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