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2 Dec 2007 23:53:42 IST

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How to calculate a "Negligible Force" ?

None

Well, my actual question was: Consider the situation, "I am appliying some force on a very big object, such that the body dosen't move at all" Calculate the force I'm appliying? If you are thinking, "Due to friction and whats the friction coefficient", then what, if the object is a 'Wall'?

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Aditya Arora

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3 Dec 2007 00:00:04 IST

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See the next one !!!

srry i posted this one by mistake

Aditya Arora

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3 Dec 2007 00:01:10 IST

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Well, if its a wall then yr object is getting a normal reaction from the wall.

And if yr object doesn't move at all, Normal Reaction = Force applied

Lokesh $ardana

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3 Dec 2007 00:18:43 IST

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yeah ! aditya is right ..........
Practically if you want to find out .......how much force you are exerting on wall.........follow the steps:
1)Hang a flat weighng machine(usually used in hospitals and health clubs to measure ur weight) on wall.
2)try to push the machine against the wall by exerting as much force as u can........
3)machine will show ur force applied in kg.wt.

actually weighing machine is designed to measure the normal reaction.........

cheers!!!!!!

harsh _27

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3 Dec 2007 12:33:06 IST

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if u draw a free body diagram of ur body ....then 2 forces will be acting on u in horizontal direction.....they are friction force b/w ur legs and ground and the normal force applied by the wall on u ....since u r not moving, they must be balanced ...so normal force b/w u and wall =force applied by u on wall= friction force applied by the ground on u...

edison

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3 Dec 2007 12:56:45 IST

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From physics point of view if u apply some force on the wall and if it does not move then obviously work done W = F.d = 0

Thus there is no work done at all as there is no displacement caused in the wall.

Moreover force applied on body produces some acceleration in it thus

F = ma, here wall does not move thus a = 0

so F =0

This seems to be an interesting situation as you are applying tremendous force but still the force comes out to be zero. The force though can be several orders of magnitude say 10000Newton or more, but still from F = ma, it comes out to be zero.

This not anamoly as the force applied is not able to overcome the internal forces of wall which is preventing it from being displaced and thus not allowing any acceleration in the wall, so this F is nothing but net force on the wall.And mass of wall seems to be infinite as far as applied force is concerned.

thus to find inderectly the force applied on wall i appreciate the method suggested by lokesh.

Lokesh $ardana

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3 Dec 2007 13:39:40 IST

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thanx..........

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