A small body of mass 500 g moves on a rough horizontal surface before finally stops. The initial velocity of the body is 2 m/s and coefficient of frictin is `0.3` Then, find absolute vlaue of the average pwoeer develped by the frictional force during the time of motion. (Take `g = 10 m//s^(2))`

Options

A. 1W
B. `1.5W`
C. `2 W`
D. `2.5W`

Answer

B

Explanation

As, retardation is constant, so average velocity
`v _(av) = ( u + v )/(2) = ( 2+0)/(2) = 1 m//s`
Now, friction force, `f = muN= mu mg`
Given, coefficient of friction, `mu =0.3`
Mass of body, `m = 500g = 0.5kg`
`implies f =0.3 xx0.5 xx 10`
`f =1.5N`
Average power by friction,
`P _(av) = fv _(av)`
`P _(av) =1.5 xx1 = 1.5W`