A solid sphere rolls without slipping, first horizontal and then up to a point X at height h on an inclined plane before rolling down, as shown.

The initial horizontal speed of the sphere is

Options

A. `sqrt((10gh)/(7))`
B. `sqrt((7gh)/(5))`
C. `sqrt((5gh)/(7))`
D. `sqrt(2gh)`

Answer

A

Explanation

`mgh = (1)/(2) mv^(2) + (1)/(2) (2)/(5) mR^(2) (v^(2))/(R^(2)) rArr mgh= (7)/(10) mv^(2)`
`rArr v= sqrt((10gh)/(7))`