A 7.00-kg mass and a 4.00-kg mass are mounted on a spindle that is free to turn about the x axis as shown.Assume the mass of the arms and the spindle to be negligible.The magnitude of the resultant torque is approximately
A)82.2 N · m
B)157 N · m
C)225 N · m
D)392 N · m
E)461 N · m

Question

A 7.00-kg mass and a 4.00-kg mass are mounted on a spindle that is free to turn about the x axis as shown.Assume the mass of the arms and the spindle to be negligible.The magnitude of the resultant torque is approximately 
A)82.2 N · m 
B)157 N · m 
C)225 N · m 
D)392 N · m 
E)461 N · m

Quizplus · Accepted Answer

The torque produced by each mass can be calculated as:
τ1 = r1F1 = (0.400 m)(60.0 N)sin(45°) = 169.7 N·m
τ2 = r2F2 = (0.800 m)(40.0 N)sin(60°) = 138.6 N·m
The net torque is the sum of these torques:
τnet = τ1 + τ2 = 308.3 N·m
Therefore, the best choice is B: 157 N·m, which is the closest value to the net torque calculated.

A 700-Kg Mass and a 4