question_answer

A particle is kept at rest at the top of a sphere of diameter 42 m. When disturbed slightly, it slides down. At what height h from the bottom, the particle will leave the sphere?

A)  14 m            

B)  28 m

C)  35 m            

D)  7 m

Correct Answer: C

Solution :

 The condition of slipping by particle from top is given by \[\cos \theta =2/3\] From the figure, \[h=r\cos \theta =21\times \frac{2}{3}=14\,m\] Therefore, the required height at which the particle will leave the sphere is \[=21+h=21+14=35m\]