Multiple-object systems without friction: Two bodies P and Q on a smooth horizontal surface are connected by a light cord. The mass of P is greater than that of Q. A horizontal force (of magnitude F) is applied to Q as shown in the figure, accelerating the bodies to the right. The magnitude of the force exerted by the connecting cord on body P will be

A) zero.
B) less than F but not zero.
C) equal to F.
D) greater than F.

Question

Multiple-object systems without friction: Two bodies P and Q on a smooth horizontal surface are connected by a light cord. The mass of P is greater than that of Q. A horizontal force

(of magnitude F) is applied to Q as shown in the figure, accelerating the bodies to the right. The magnitude of the force exerted by the connecting cord on body P will be

A) zero. 
B) less than F but not zero. 
C) equal to F. 
D) greater than F.

Quizplus · Accepted Answer

Since there is no friction, the tension in the cord is the same at all points. Therefore, the cord pulls back on body P with a force equal in magnitude but opposite in direction to the force it exerts on body Q. Since the mass of P is greater than Q, it will require a greater force to accelerate it at the same rate as Q. Therefore, the tension in the cord will be less than F but not zero.

Multiple-Object Systems Without Friction: Two Bodies P and Q on a Smooth