Question

A pulley block of radius 20cm is set in rotation by a weight P suspended from a string gradually unwinding from the block (Fig.). The weight was initially at rest and then began to drop with an acceleration of 2cm/sec². Find the angular velocity of the pulley at the instant the weight has travelled a distance of 100cm. Find the magnitude and direction of acceleration of point A at that instant.

Answer 1

Answer:

Explanation:

 The linear velocity of a point on the circumference of the pulley at any instant is equal to the linear velocity of the weight, i.e.,

 v = √(2aS).

When the weight has travelled a distance of 100 cm, the velocity is 20cm/sec. The angular velocity is ω = 1/sec. The acceleration of point A is the resultant of the linear acceleration a and the centripetal acceleration v²/r (Fig.):