The pull P is just sufficient to keep the 14-N block and the weightless pulleys in equilibrium as shown. The tension T in the upper cable is:
A) 14 N
B) 28 N
C) 16 N
D) 9.33 N
E) 18.7 N

Question

The pull P is just sufficient to keep the 14-N block and the weightless pulleys in equilibrium as shown. The tension T in the upper cable is: 
A) 14 N 
B) 28 N 
C) 16 N 
D) 9.33 N 
E) 18.7 N

Quizplus · Accepted Answer

Since the block is in equilibrium, the forces acting on it must be balanced. The tension T in the upper cable is pulling up on the block with a force of T, and the weight of the block is pulling down with a force of 14 N.

Therefore, we can write:

T = 14 N

as the tension in the cable.

(Note that the forces acting on the pulleys also contribute to the forces in the cables, but since they are weightless, we can assume their forces are negligible.)

So the correct answer is choice C, 16 N.

The Pull P Is Just Sufficient to Keep the 14-N