A lift is moving downwards. A body of mass `2 kg` kept on the floor is pulled horizontally and is in motion. If the coefficient of friction between the body and floor is `1 // 2`, find the friction acting on the body if (a) lift is moving with a uniform velocity and (b) lift is moving with acceleration `5 m//s^(2)` in the downward direction.

Explanation

(a) Life its moving with uniform velocity
`N_(0) = 20 N`
`f = mu N_(0) = (1)/(2) xx 20 = 10 N`
(b) `darr : 20 - N_(0) = 2a = 2 xx 5`
`N_(0) = 10 N`
`f = muN_(0) = (1)/(2) xx 10 = 5 N`