Physics help

jai6638

Golden Member
Apr 9, 2004
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hey ... have a physics exam tomorrow am havin tryin to solve this problem but to no avail.. anyh elp is appreciated :

If you use a horizontal force of 30N to slide a 12 kg wooden crate across a flood at a cnostant velocity, what is the coefficient of kinetic friction between the crate and the floor?


thanks much
 
Aug 10, 2001
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Unless it's a trick question or something, it's a very simple problem:

Since the 30N force is being applied entirely in the horizontal direction, the normal force of the floor on the block just equals the weight of the block. And since the the block is moving at a constant velocity, the force of friction must equal the 30N force (but in the opposite direction, of course).

Normal force=(12)(9.8)=117.6N

30=(117.6)*(coefficient of kinetic friction)
 

jai6638

Golden Member
Apr 9, 2004
1,790
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Originally posted by: Vespasian
Unless it's a trick question or something, it's a very simple problem:

Since the 30N force is being applied entirely in the horizontal direction, the normal force of the floor on the block just equals the weight of the block. And since the the block is moving at a constant velocity, the force of friction must equal the 30N force (but in the opposite direction, of course).

Normal force=(12)(9.8)=117.6N

30=(117.6)*(coefficient of kinetic friction)

damn.... i was doin the same thing but a friend of mine told me that it was wrong!

anyways, thanks much .. appreciate it...