General questions: Two objects, each of weight W, hang vertically by spring scales as shown in the figure. The pulleys and the strings attached to the objects have negligible weight, and there is no appreciable friction in the pulleys. The reading in each scale is
A) W.
B) more than W, but not quite twice as much.
C) less than W.
D) 2W.
E) more than 2W.

Question

General questions: Two objects, each of weight W, hang vertically by spring scales as shown in the figure. The pulleys and the strings attached to the objects have negligible weight, and there is no appreciable friction in the pulleys. The reading in each scale is 
A) W. 
B) more than W, but not quite twice as much. 
C) less than W. 
D) 2W. 
E) more than 2W.

Quizplus · Accepted Answer

Since the two objects are hanging vertically, the tension in the string connecting them must be equal to their weight (W), as there is no horizontal force acting on them. This means that each spring scale must be measuring a force equal to W in order to support the weight of each object. Therefore, the reading in each scale is W.

General Questions: Two Objects, Each of Weight W, Hang Vertically