Why does weighing on carpet make you appear heavier?

  • Context: High School 
  • Thread starter Thread starter GummiCandy
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SUMMARY

The discussion centers on the phenomenon of weighing oneself on carpet versus a solid surface, with participants noting that scales often show lower readings on carpet. Key insights reveal that the scale's design, which includes feet intended for flat surfaces, can lead to inaccurate readings on uneven surfaces like carpet. The compression of carpet under weight can absorb some of the force, resulting in a lower weight measurement. Participants also emphasize the importance of using scales on flat, rigid surfaces for accurate readings.

PREREQUISITES
  • Understanding of basic physics principles related to weight and pressure.
  • Familiarity with how mechanical scales operate.
  • Knowledge of the effects of surface stability on weight measurements.
  • Awareness of the scientific method for conducting experiments.
NEXT STEPS
  • Research the mechanics of different types of weighing scales, including digital and mechanical models.
  • Explore the impact of surface materials on weight measurement accuracy.
  • Learn about the principles of pressure distribution in physics.
  • Investigate common misconceptions in weight measurement and how to avoid them.
USEFUL FOR

This discussion is beneficial for physics students, mechanical engineers, and anyone interested in understanding the principles of weight measurement and the effects of surface conditions on accuracy.

GummiCandy
I've been struggling with this question for some time now. The question is rather simple. I'm sure most of you people have try weighing yourself on carpet and find out that it's heavier. So, why is that? How come when you weigh yourself on carpet, the measure you get is heavier than if you measure if on solid ground?

Thanks in advance!
 
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I'm sure most of us have never observed any such effect.

- Warren
 
Originally posted by GummiCandy
I've been struggling with this question for some time now. The question is rather simple. I'm sure most of you people have try weighing yourself on carpet and find out that it's heavier. So, why is that? How come when you weigh yourself on carpet, the measure you get is heavier than if you measure if on solid ground?

Thanks in advance!

this question drives me crazy
how can Gummicandy think that most of us have
tried weighing ourselves on carpet?
Gummicandy must be making this up as a clever joke to play on us.

actually Gummi is "rubber" in German so if you give someone
a piece of candy made of rubber that is a practical joke
designed to catch the gullible
it is an inventive scheme in extremely bad taste
 
That's odd, this is not the first time I have heard this question. The only answer I can think of is that the weight goes through the centre of the scales (where the weighing mechanism is) more, rather than acting through a larger area than it would on a flat surface.
 
That actually makes sense... the scale is most likely designed with some "feet" on the bottom which are supposed to be placed on a flat surface, and the device is designed to measure the pressure between its top plate and the structural members connected to those feet. If you place the scale on carpet, the scale is supported all over its bottom, not just on its feet -- and it will definitely affect its reading.

On the other hand, it would seem to me that the scale would read low, not high, in such a circumstance.

- Warren
 
Originally posted by chroot
That actually makes sense... the scale is most likely designed with some "feet" on the bottom which are supposed to be placed on a flat surface, and the device is designed to measure the pressure between its top plate and the structural members connected to those feet. If you place the scale on carpet, the scale is supported all over its bottom, not just on its feet -- and it will definitely affect its reading.

On the other hand, it would seem to me that the scale would read low, not high, in such a circumstance.

- Warren

Chroot that is the same answer I gave last time, I told them it must be due to some external factor (as an uneven surface would mean that the weight would be acting at a differnet angle to scale reducing it's vector in the direction of the scale), but seening the same question again the only explantion I can think of is that the scal;e is calibrated for weight acting through the surface evenly, but the uneven surface may mean that it acts through the weighing mechanis more than the outer edges.
 
Originally posted by jcsd
Chroot that is the same answer I gave last time
I know, that's why I said "That [your answer] actually makes sense." Sorry for not quoting you. I was just thinking aloud. :)

- Warren
 
Using the "scientific method" (heard of it?), I went to my scale on the tile bathroom floor and weighed my self (a truly horrible experience!) then moved the scale to a carpeted floor and weighed myself again. The weight on the carpet was about 8 pounds LOWER, not higher.
 
Originally posted by chroot
I'm sure most of us have never observed any such effect.

- Warren

Hold on. Not so fast. We don't know what kind of scale GummiCandy has.

Here's what I'm thinking: When you step on a scale your weight shifts, i.e. you first put one foot on and then you put the other foot on. A scale may only work properly when the weight is spread evenly over the top. Perhaps what happens is that the matting of the carpet compresses unevenly as the first foot steps on and then when you put the second foot on the scale does not restore to normal.

That's just a quick thought - i.e. not that you *reall* weigh more but that GummiCandy has a weird scale

Pete
 
  • #10
Originally posted by HallsofIvy
Using the "scientific method" (heard of it?)
Yeah, it means you're not afraid of doing mad things . Weighed myself on my bed. The reading was 5 kg lower than on tiled floor.
 
  • #11
Originally posted by HallsofIvy
Using the "scientific method" (heard of it?), I went to my scale on the tile bathroom floor and weighed my self (a truly horrible experience!) then moved the scale to a carpeted floor and weighed myself again. The weight on the carpet was about 8 pounds LOWER, not higher.


EXACTLY...that is what makes sense right? On the carpet part of your weight goes to crushing (no offense ) the carpet, thereby making the apparent, overall weight of the person LESS, not more. Thanks for the 'proof' Ivy!

fizixx
 
  • #12
My Mechanics lecturer mentioned this carpet thing as well. He said it was simply the instability of the surface under the scales.
 
  • #13
Originally posted by Adam
My Mechanics lecturer mentioned this carpet thing as well. He said it was simply the instability of the surface under the scales.

Wow! You mean I was right? Cool! I love it when I take a wild shot and get it right. Thank you for brining this here.

Pete
 
  • #14
Very humorous and entertaining posts , I especially liked Halls of Ivy's 'scientific method'.
Unfortunately I am totally unable to participate in the research efforts here. You see, my bathroom scale kept showing a higher reading every several months. So I did what ever good scientist does when appliances go bad...I donated it to the Salvation Army.

However, such a drastic measure was probably premature. I realize now there was another possibility for the higher reading...a change in the value of G !

Creator
 
Last edited:
  • #15
Originally posted by chroot
I'm sure most of us have never observed any such effect.

- Warren
I don't know about you, but almost all scaling devices in Israel come with the warning "to be used on flat rigid surface only". And ever since I was a child I knew that you had to weigh yourself on the floor only. :)

Then again I also believe in the tooth-fairy, so you never know! ;)
 
  • #16
This thread looks to be a bit old, but to put you all out of your misery the reason weighing yourself on carpet gives a lighter result is because the carpet acts as an absorber, thereby taking some of the weight and reducing the load on the scales.

Adam - I hope your mechanics lecturer isn't teaching you anything important!
 
Last edited:
  • #17
Amber...

Your post is a little redundant (see my post on page 1), but always good to see reasonable responses to fun questions. :)

f- :wink:
 

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