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 \[\cos \theta =2\text{/}3\] 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 \[=21+h=21+14=35\,m\]