A 120 N traffic light is located at the midpoint of a cable between two poles. The cable makes an angle of 30° to the horizontal at each pole. What is the tension in the cable? Ignore the mass of the cable.
A) 60.0 N
B) 90.0 N
C) 140 N
D) 110 N
E) 120 N

Question

Quizplus · Accepted Answer

The tension in the cable is equal to the weight of the traffic light because the system is in equilibrium, and the vertical component of the tension must balance the weight of the light. Since the angles and the situation are symmetrical, the tension is directly supporting the weight of the traffic light, which is 120 N.

A 120 N Traffic Light Is Located at the Midpoint