A body of mass m slides down a plane inclined at an angle `alpha`. The coefficient of friction is `mu`. Find the rate at which kinetic plus gravitational potential is dissipated at any time t.

Options

A. `mu mtg^(2) cos alpha`
B. `mu mtg^(2) cos alpha (sin alpha - m cos alpha)`
C. `mu mtg^(2) - sin alpha`
D. `mu mtg^(2) sin alpha (sin alpha - m cos alpha)`

Answer

B

Explanation

`P = F.V`
So `= mg(sin alpha - mu cos alpha) mu g cos alpha t`
`= mu mg^(2) t(sin alpha - mu cos alpha) cos alpha`.