Question

A body crosses the topmost point of a vertical circle with critical speed. What will be its centripetal acceleration when the string is horizontal:

a} 1g

b} 2g

c} 3g

d} 4g

Answer 1

The correct answer is c) 3g 

$V=\sqrt{3gr}$ 

$a=\frac{v^2}{r}$ 

Then ,  

$a=\frac{3gr}{r}=3g$