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I'm thinking something like if I take a box and place a weighing machine and an object inside it...then if i increase the pressure inside that box would i observe any change the weight of the object? This came to my mind while studying about friction and viscosity. And i was thinking does pressure effect friction....It was written no but i thought it should cause i think the weight would increase if i increase the pressure and so the normal contact force increases which would cause the friction to increase as well...m i right?

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  • $\begingroup$ What type of weighing machine? Do you zero the weighing machine, after increasing the pressure, before putting the object on it? $\endgroup$
    – user253751
    Apr 18, 2020 at 22:45
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    $\begingroup$ Please type your question with proper grammar. $\endgroup$
    – Andrew
    Apr 18, 2020 at 23:18
  • $\begingroup$ Im sorry english is not my 1st language so i might have some grammatical mistakes $\endgroup$
    – Meow
    Apr 20, 2020 at 12:50

2 Answers 2

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The weight of the object would increase as thew atmospheric pressure increases, however the difference is negligible.

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The usual model for friction states that the friction force is proportional to the normal contact force, which is the response to the pressure. Then, increasing the pressure inside the box will increase the normal forces of its internal walls. However, the weight of something at the surface of the Earth (be it a box with an object or whatever) depends only on its mass, not on the internal processes of the weighted object.

Changing the pressure inside an object doesn't alter its mass, so no (unless you change the pressure by adding air in the box, but then you are changing the mass as well).

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  • $\begingroup$ Why no? The weighing machine is also inside the box, so when i will increase the pressure inside the box the molecules inside the box will now collide frequently with my object as well right? So that will increase the pressure on my object and as a result wont i observe an increase in weight in the machine? $\endgroup$
    – Meow
    Apr 20, 2020 at 12:50
  • $\begingroup$ They will collide with the upper part of the box as well, which cancels this effect $\endgroup$ Apr 20, 2020 at 14:42
  • $\begingroup$ But i m not weighing the box. Im weighing an object inside the box $\endgroup$
    – Meow
    Apr 20, 2020 at 15:38

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