Three Identical 3

Multiple Choice

Three identical 3.0-kg cubes are placed on a horizontal surface in contact with one another.The cubes are lined up from left to right and an 18-N force is applied to the left side of the left cube causing all three cubes to accelerate to the right.If the cubes are each subject to a frictional force of 3.0 N,what is the magnitude of the force exerted on the middle cube by the left cube in this case?

A) 18 N
B) 6 N
C) 12 N
D) none of the above