A man in a gym is holding an 8.0-kg object at arm's length,a distance of 0.55 m from his shoulder joint.What is the torque about his shoulder joint due to the object if his arm is horizontal?
A)0.24 N ∙ m
B)4.4 N ∙ m
C)43 N ∙ m
D)15 N ∙ m
E)0 N ∙ m

Question

Quizplus · Accepted Answer

The torque about the shoulder joint is given by the formula:
Torque = Force x Distance x sin(angle between force and lever arm)
Since the arm is horizontal, the angle between the force and the lever arm is 90 degrees, so sin(90) = 1. Therefore,
Torque = Force x Distance
The force here is the weight of the object, which is given by:
Force = mass x gravity
Force = 8.0 kg x 9.8 m/s^2
Force = 78.4 N
Now we can calculate the torque:
Torque = Force x Distance
Torque = 78.4 N x 0.55 m
Torque = 43.12 N∙m
Therefore, the answer is C) 43 N∙m.

A Man in a Gym Is Holding an 8