Three Identical 6

Multiple Choice

Three identical 6.0-kg cubes are placed on a horizontal frictionless surface in contact with one another.The cubes are lined up from left to right and a 36-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 6.0 N,what is the magnitude of the force exerted on the middle cube by the left cube in this case?

A) 12 N
B) 24 N
C) 36 N
D) none of the above