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 force is applied to the left side of the left cube causing all three cubes to accelerate to the right at 3.0 m/s².What is the magnitude of the force exerted on the middle cube by the left cube in this case?

A) 18 N
B) 36 N
C) 27 N
D) 21 N
E) none of the above