Mashy 3 years ago Question on weight What does our usual balancing scale denote?? mass or weight.. So when we stand it denotes say 70 kg... my question is, does it measure our force and then divide by 9.8 and give the result as 70kg.. in which case its my mass?? or whether it directly shows the force value.. in which case its newtons and my mass is in reality 7kg?

1. Ishaan94

weight.

2. Ishaan94

the force exerted by earth. the weight not the mass.

3. Mashy

so you mean to say my mass is 6kg??? or does it actually divide by 9.8 and give the final answer..??

4. Ishaan94

yes, your mass i 6kg and mine is 9:(

5. Mashy

Some sources say.. the weighing scale calculates the force and divides it by 9.8 and so it actually does give the value of mass in kg itself.. in which case my mass really is 70kg and yours 90kg..

6. Ishaan94

hmm i think it depends more on the weigh scale, like the most common one (in the markets) doesn't do all the calculation but maybe the ones in laboratory does it.

7. Mashy

how is that possible.. cause in both the scales we get the same result.. we would get 70 and 90 as the value itself

8. Ishaan94

noooo, the normal weighing scale only calculates our weight not our mass.

9. Ishaan94

hmm most weighing machins work on the newtons third law the measure the reaction of the force of the gravity. you can verify this by weighing yourself in a lift.

10. Mashy

http://home.howstuffworks.com/inside-scale1.htm i just read this... according what i just understood... the arrangement is such that.. the net force is divided by 12... so it does provide the actual mass

11. Mashy

ishaan obviously it would change cause then the calculation would become.. something like 7kg * 10.5 (due to upward acceration) divided by 9.8..

12. rs32623

Although it gives us the weight. It does not make any difference. Because it is relative.Suppose i say weight of substance 1 is A N and weight of substance 2 is B N. Now you will say weight of a is A/9.8 Kg & weight of B is B/9.8Kg. so it didn't make any difference because still the ratio is same.

13. Mashy

i mean't 70kg*10.5/9.8

14. Ishaan94

hmm @apoorvk @experimentX

15. Ishaan94

until now i thought it was the force not the mass itself.

16. Mashy

17. experimentX

Gravitational force <---- a property of objects having a property called mass <-- I think

18. Ishaan94

mashy see this. it's the standard 1 kg mass http://www.justervesenet.no/GetFile.aspx/images/epii_id/730/epit_id/1 mass not weight

19. Ishaan94

the thing inside the glass chamber

20. Ishaan94

or column

21. Vincent-Lyon.Fr

Imagine you are on the Moon with the same scale. If the reading is the same as on Earth, it means your balance is built to measure masses. If the reading is different, it measures weights. Modern balances with strain sensors or springs measure weights. Balances with two plates, where you add calibrated masses on one side measure masses. In all cases, whether the balance measures weights or masses, the reading is always converted into a mass equivalent. Standard electronic kitchen scales can be calibrated depending if you live near the poles or near the Equator, because g varies slightly with latitude.

22. Ishaan94

i don't think normal or common weighing machines measure the mass.

23. Mashy

So according to vincent.. the final value is mass.. and hence my mass is 70kg

24. Mashy

and vincent.. hw is it possible to measure mass????? unless you use a balancing scale

25. Ishaan94

read it again, he said it measure the weight

26. Mashy

@vincent.. i didn't read that one part.. sorry :D.. so finally i understand my mass is 70 kg... ishaan.. he said it finally converts it into mass

27. rs32623

@Mashy When you are talking about mass first thing you have to admit is It is not going to change. If you take your weighing scale to the moon & measure yourself it would give you value different from that of earth. Although we measure weight of a substance we measure it in Kg. That should be counted in newton. So for the calculation purpose it doesn't give an error whether you use Kg or Newton.

28. Mashy

29. Mashy

ll brb after dinner

30. Ishaan94

hmm you can try this on your own. get into a lift if the reading changed then it's weight if it doesn't then it's mass.

31. Ishaan94

weighing yourself in a lift

32. apoorvk

Okay folks ever heard of "Kilogram Weight"?

33. apoorvk

1N is basically the weight of one Kg on earth. Now your weighing machine definitely doesn't measure 'mass', as mass is a constant. Now if you were on moon, you would suddenly go lighter, right? (good for you if you're overweight :p) Wrong. You mass is what it is. It doesn't change Your weight does. A balance just measures the force on its top surface. It shows your 'weight'.

34. Vincent-Lyon.Fr

To measure a mass directly, the easiest way is to compare it to a standard, copied from the standard kilogramme kept in Sèvres (Fr) by BIPM (Bureau International des Poids et Mesures). You can also give the mass a velocity and convert its kinetic energy in some other form of energy which you know how to measure. You can exert a known force and measure the acceleration.

35. Ishaan94

mashy do you think this weighing balance accounts for gravitational acceleration. http://blog.kirgs.com/images/balance_scales.jpg or this one, http://i.istockimg.com/file_thumbview_approve/579605/2/stock-photo-579605-old-fashioned-weighing-scales.jpg

36. Ishaan94
37. Mashy

ishaan when it comes to using balancing scales.. if the other side has a standard like 1kg mass or 2kg mass equivalent.. then you can measure directly in mass itself.. where as in the case of the other weighing scale .. there could be internal mechanism by which it divides

38. Vincent-Lyon.Fr

It does not actually divide. It is just the scale on which you read is written directly in kilogrammes. It actually measures weights not in newtons, but in kilogramme-forces.

39. Mashy

appoorvk.. a weighing scale may work as how i mentioned and show my mass.. and it would still show error on moon, just because it shows error on moon doesn't mean it DOES not display mass..

40. Ishaan94

there is a reason why we call it weight not mass mashy.

41. Mashy

So vincent i finally ask you the question... what is your mass?

42. Mashy

ishaan if we call it weight and we measure in kg.. which is error... it could actually be mass and we call it weight :D

43. Mashy

44. Mashy

apoorv i perfectly understand the difference between mass and weight :-/

45. Ishaan94
46. apoorvk

|dw:1335198265200:dw|

47. Mashy

Ishaan.. its still written in yahoo answers that it is CALIBERATED ... to give the final answer in kg

48. Mashy

see even apoorve says that female weighs 900N.. which means i weight 700N on earth :P

49. Ishaan94

mass won't change with location or speed (until you chose to travel at very high speeds). why don't you try measuring your weight in an elevator?

50. Mashy

Ishaan.. as i told you... a weighing scale which operates as I SAID will also show an error in elevator.. My mass is 70kg (according to me) .. how the elevator calculates is 70*9.8 /9.8 = 70 final output in elevator it would calculate as 70*12(say)/9.8 = something more than 70.... so you see.. def it ll give error.. doesn't mean it cannot give mass

51. Ishaan94

i know one thing that weighing machines only measure the reaction to the force of gravity. and if they do, then they don't show mass.

52. Mashy

Ishaan, why can't after finding the force, divide it???

53. apoorvk

WHAT THE HECK IN THE WHOLE HOLY HELL DOES AN ELEVATOR DO, FIRST OF ALL?? @Mashy

54. apoorvk

and @Ishaan94 too. whaddya folks think it does?

55. Mashy

apoorvk.. an elevator increases or decreases acceleration ( if its going on... acceleration of the elevator adds to g.. so your weight would be m(a+g).. )

56. Ishaan94

mass won't change. mass can't change until you decide to travel at high speeds or cut yourself. |dw:1335198965700:dw|here the normal reaction is \(N = mg - mg/2\).

57. Mashy

going up* i meant

58. rs32623

@Mashy The final answer of your question is weighing scale measures your force but it gives us the mass as long as you are on earth because it is calliberated with the standard 1Kg mass. If a body on earth exerts the same amount of force as the standard 1Kg mass exerts then we call it as 1Kg. Now suppose we take our weighing scale to the moon. It will no longer give you the mass because as per the definition of mass it is constant in that case it would measure your force & give us a different value that is neither mass not weight. Mu weight is 50*9.8 N. And my mass is 50Kg. You see the people use the word weight erroneously in place of mass. So if i say my weight is 50 Kg i am wrong because it is the mass .

59. Mashy

I agree with rs.. thats what i wanted.. my mass is 70kg.... ishaan i understand what you say... you are not understanding what I am saying? :-/

60. Mashy

ishaan.. mass is a constant yes.... but the scale USES force TO calculate MASS.. thats what I am saying!..

61. Ishaan94

so 90 kg mass and 900 newton force?

62. Mashy

Ishaan yes.. i think so.. and besides your diagram is wrong... when the elevator goes up, your weight increases :P

63. rs32623

@Mashy you are right. weighing balance uses the interpretation of weight but gives us the value that is mass. That is why they denote it in Kg & not in the Newton.

64. apoorvk

okay folks. first we find the force everytime. the force is what the reading on the balance shows. then we find that the acceleration of the body. now we apply m=Fnet/a, and that gives you the mass. *always constant*

65. Mashy

Ok.. unless anyone has any other opinion (other than what I and rs32 finally agree on).. i would like to close this discussion.. thank you all for helping me.. a great hug :D

66. apoorvk

That is exactly what we mean by 'kg weight', mashy

67. Ishaan94

ohh no the diagram is right, i meant to use + sign the minus sign is a typo

68. Mashy

yess apoorvk.. i agree! thank you!!!

69. rs32623

@Mashy thank you a lot. This was a great discussion. you were awesome:)

70. Ishaan94

"In commercial and everyday use, the term "weight" is usually used to mean mass ..." from wikipedia hmm no one told me this before. :/ or maybe i didn't listen

71. tabish

Okey, Freinds... let me help you........... It actually measure MASS.... SO my mass is 60 KG..... These instrument are calibrated such that, first it calculate Normal Reaction than than it divide it by 9.8............................... Mass does not change right, but why it changes in LIFT and on MOON....... ANSWER IS: In lift normal reaction changes, thats why........ you have to ensure that normal reaction should be only because of your weight.. ON Moon: again normal reaction changes, but instrument is still in calibration with 9.8, thats whyy it givess diiferent result............