In the above question, the average power delivered by gravity is

Options

A. (a) `-mg u cos alpha`
B. (b) `-mgu sin alpha`
C. (c) `-(mgucos alpha)/(2)`
D. (d) `-(mgusinalpha)/(2)`

Answer

D

Explanation

Average power`lt P gt (lt W gt)/(t)=-(mu^2sin^2alpha)/(2((usinalpha)/(g)))`
`=(-mgusinalpha)/(2)`
[Since time taken to go from O to `P=u sin alpha//g`]