A block of mass $m$ is moving with a constant acceleration a on a rough plane. If the coefficient of friction between the block and ground is $\mu $, the power delivered by the external agent after a time $t$ from the beginning is equal to
A$ma^2t$
B$\mu mgat$
C$\mu m(a + \mu g)\, gt$
D$m(a + \mu g)\, at$
Medium
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D$m(a + \mu g)\, at$
d $F-f=\mathrm{ma}$
$F=f+\mathrm{ma}$
Power $(\mathrm{P})=\mathrm{Fv}=(\mathrm{f}+\mathrm{ma}) \mathrm{v}=(\mu \mathrm{mg}+\mathrm{ma})$ at
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