Question

Blocks A and B of masses M and 3M, respectively, are on a horizontal surface of negligible friction. A horizontal force FA is exerted on block A, as shown. If the force exerted by block B on block A has a magnitude F, the magnitude of FA is

a. 1/4 F
b. 3/4 F
c. F
d. 4/3 F
e. 4F

Answer 1

The magnitude of FA can be found by considering the forces on block A. The force exerted by block B on block A has a magnitude of F, and according to Newton's third law, the force exerted by block A on block B is also F. Therefore, the magnitude of FA is 1/4 F.

Step-by-step explanation:

The magnitude of FA can be found by considering the forces on block A. The force exerted by block B on block A has a magnitude of F. According to Newton's third law, the force exerted by block A on block B is also F. Since there is no friction and neglecting the weight of block A, the net force on block A is the force FA exerted on it minus the force exerted by block B (F). Therefore, the magnitude of FA is 1/4 F (Option a).