A block of mass M slides down a rough inclined surface of inclination `theta` and reaches the bottom at speed at 'v' . However , if it slides down a smooth inclined surface of same length and same inclination , it reaches the bottom with the speed kv. Coefficient of friction between the block and the rough incline is :

Options

A. `sin theta (k^(2) -1)`
B. `((k^(2) - 1)/(k^(2))) tan theta `
C. `(( k^(2) + 1)/( k^(2))) cos theta`
D. `(k^(2) - 1)/(k^(2))`

Answer

B