Two identical blocks are pulled along a rough surface as suggested in the figure. Which one of the following statements is false?
A)The coefficient of kinetic friction is the same in each case.
B)A force of the same magnitude is needed to keep each block moving.
C)A force of the same magnitude was required to start each block moving.
D)The normal force exerted on the blocks by the surface is the same for both blocks.
E)The magnitude of the force of kinetic friction is greater for the block on the right.

Question

Two identical blocks are pulled along a rough surface as suggested in the figure. Which one of the following statements is false? 
A)The coefficient of kinetic friction is the same in each case. 
B)A force of the same magnitude is needed to keep each block moving. 
C)A force of the same magnitude was required to start each block moving. 
D)The normal force exerted on the blocks by the surface is the same for both blocks. 
E)The magnitude of the force of kinetic friction is greater for the block on the right.

Quizplus · Accepted Answer

The block on the right is being pulled at an angle, which means that the normal force exerted by the surface is smaller than the weight of the block. This in turn means that the force of kinetic friction is greater on the block on the right, as friction is directly proportional to the normal force. Therefore, statement E is false. Statements A, B, C, and D are all true.

Two Identical Blocks Are Pulled Along a Rough Surface as Suggested