Concepts Of Physics MCQ Edition [Volume 1]PhysicsCircular Motion
A hemispherical bowl of radius R is rotated about its vertically maintained axis of symmetry. A small block is placed inside the bowl at a position where the radius vector forms an angle with the vertical. The block rotates alongside the bowl without experiencing any slipping. The coefficient of friction between the surface of the bowl and the block is . Determine the range of the angular speed for which the block av
Options
- A[ g( - ) R ( + ) ]^ 1/2 to [ g( + ) R ( - ) ]^ 1/2
- B[ g( - ) R( + ) ]^ 1/2 to [ g( + ) R( - ) ]^ 1/2
- C[ g( + ) R ( + ) ]^ 1/2 to [ g( - ) R ( - ) ]^ 1/2
- D[ g( - ) R ( + ) ]^ 1/2 to [ g( + ) R ( - ) ]^ 1/2
Correct answer
A. [ g( - ) R ( + ) ]^ 1/2 to [ g( + ) R ( - ) ]^ 1/2
Step-by-step solution
Consider a block of mass m rotating in a horizontal circle of radius r = R . The forces acting on the block are the normal reaction N , the weight mg , and the frictional force f . For the minimum angular speed _ min , the block has a tendency to slip downwards, so the limiting frictional force acts upwards along the tangent to the bowl. Balancing forces in the vertical direction: N + f = mg The net force towards the center provides the centripetal acceleration: N - f = m _ min ^2 r Using f = N and r = R , we get: