A body of mass 2 kg is pulled with a velocity `2 m cdot s^(-1)` on horizontal surface. What will be the heat produced in 5s, if the coefficient of friction between the body and the surface is 0.2? Given, `J = 4.2 J cdot cal^(-1) , g = 9.8 m cdot s^(-2)`.

Explanation

Force of friction on the body, `F = mu mg`
So the work done, `W = Fs = mu mg cdot vt`
`:.` Heat produced, `H = W/J = (mu m g v t)/(J)`
`=(0.2 xx 2 xx 9.8 xx 2 xx 5)/(4.2)`
`= 9.33 cal`.