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Homework help regarding forces of friction and their directions

  • Thread starter MechRocket
  • Start date
14
0
The Problem

http://img15.imgspot.com/u/07/118/16/friction.JPG [Broken]

What I Think

http://img15.imgspot.com/u/07/118/16/think.JPG [Broken]

The Correct Solution

http://img15.imgspot.com/u/07/118/16/solution.JPG [Broken]

What Is Confusing Me

Shouldn't the force of friction on the slab be pointed to the left? I knew the force of friction on the block is pointed to the left (because friction will oppose movement), so I naturally assumed this force to the left also acts on the slab (the two surfaces are touching after all).

I just cannot see why the friction force on the slab is to the right.

Thanks a lot! :)
 
Last edited by a moderator:
2,981
2
Picture instead of the slab remaining stationary and the block sliding right, the block standing still and i the slab is sliding left. . . then which direction will oppose motion direction?
 

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