Q.

A body of mass 'm' connected to a massless and unstretchable string goes in verticle circle of radius 'R' under gravity g. The other end of the string is fixed at the center of circle. If velocity at top of circular path is ngR, where n1, then ratio of kinetic energy of the body at bottom to that at top of the circle is          [2025]

1 nn+4  
2 n+4n  
3 n2n2+4  
4 n2+4n2  

Ans.

(4)

v0=v2+2g(2R)

v0=n2gR+4gR

 kbottomktop=v02v2=n2+4n2