A block of weight 30N lies on a horizontal table top. A force of 40N acts parallel to the surface of the table top, but does not cause the block to move. What is the magnitude of the frictional force between the block and the table?

Question

cwrw238 · Answer

if the block is just about to move then the friction is equal to mR  where m = coefficient of friction and R = normal reaction of the block.

normal reaction  R = weight of the block = 30N 

the frictional force 30m = to the force 40N

30m = 40 

total frictional force is 40N
and coefficient of friction between the block and the horizontal surface =  4/3

anonymous · Answer

Thank You.