Homework help regarding forces of friction and their directions

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SUMMARY

The discussion centers on the forces of friction acting on a slab and a block in a physics problem. The user expresses confusion regarding the direction of the friction force on the slab, believing it should point left, similar to the friction force on the block. However, the correct solution indicates that the friction force on the slab actually points to the right, opposing the motion of the slab when the block slides to the right. This highlights the importance of understanding the interaction between surfaces in contact and the direction of opposing forces.

PREREQUISITES
  • Understanding of Newton's laws of motion
  • Basic principles of friction, including static and kinetic friction
  • Knowledge of free-body diagrams for visualizing forces
  • Familiarity with the concept of relative motion between objects
NEXT STEPS
  • Study the principles of static versus kinetic friction in detail
  • Learn how to construct and analyze free-body diagrams
  • Explore examples of friction in different physical scenarios
  • Investigate the effects of surface materials on frictional forces
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Students studying physics, educators teaching mechanics, and anyone interested in understanding the dynamics of frictional forces in real-world applications.

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The Problem

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

What I Think

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

The Correct Solution

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

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:
Physics news on Phys.org
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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