Question

An elevator initially at rest supported by a cable passes over a Pulley of radius 0.4 metre. It is accelerated upwards with 0.6 metre per second square . find number of rotations made by pulley during 10 second

Answer 1

Answer:

12 turns.

Explanation:

Since, the elevator was initially at rest position hence the initial velocity of the elevator must be zero. So, on applying Newtons second law equation we will get that S=ut+1/2at^2. S=1/2at^2 where a is the acceleration given 0.6 m/s^2. The time t given as 10 seconds. So, the S=1/2*0.6*10*10 = 30 m.

Now, the pulley having a radius r or 0.4 meter. So, the number of rotations will be 2πr or 2*3.14*0.4=2.5 m. So, to cover 30 meter, the number of turns required will be 30/2.5 which is 12 turns.

Answer 2

Answer:

Explanation:

s=1/2at2

distance=2[3.14][0.4]=2.5