Question

A mass is hanging from the end of a horizontal bar that pivots around an axis through its center, but it is being held stationary. The bar is then released and begins to rotate. As the bar rotates from horizontal to vertical, the magnitude of the torque on the bar: ________

Answer 1

Answer:

The torque decreases because as the hanging mass goes down, the moment arm about the pivot point decreases. Since the torque is directly proportional to the length of the moment arm, torque decreases.