A block of mass m is moving with a constant acceleration a on a rough horizontal plane. If the coefficient of friction…..

Q:A block of mass m is moving with a constant acceleration a on a rough horizontal plane. If the coefficient of friction between the block and ground is μ , the power delivered by the external agent after a time t from the beginning is equal to

(A) ma²t

(B) μmgat

(C) μm(a + μg)gt

(D ) m(a + μg)at

Sol: Instantaneous power delivered = P = F^→.v^→ = F v

where, F – f = ma

F = f + ma

P = (f + ma) v

Put f = μmg

P = ( μmg + ma)v

P = m(a + μg).at