The $49-$lb

block rests on the rough surface for which the coefficient of kinetic friction is $\backslash$mu k

$=0\mathrm{.}2.$ A force F$=(40+$s$2)$lb

$,$ where s

is in ft

$,$ acts on the block in the direction shown. The spring is originally unstretched $($s

$=0)$ and the block is at resDetermine the power developed by the force the instant the block has moved s

$=1\mathrm{.}5$ ft

$.$

Express your answer in units of horsepower to three significant figures.