Question

A particle is moving in a circular orbit with a constant angular acceleration. After a certain time t has elapsed from the beginning of the motion, the angle between the total acceleration and the direction along the radius R and towards the centre becomes equal to π/4. The angular acceleration of the particle is :

• A. 1/t²
• B. R/2t²
• C. R/t²
• D. 2/t²

Answer 1

Answer: (B)

R/2t²

Answer 2

For Block F = 20.2 = 40 N

As man exerts 40 N force on block, block exerts 40N force on the boy, in opposite direction. The boy is also moving with same acceleration. If f is friction force exerted by the surface on the boy then

f – 40 = 50.2

f = 140 N.