Part A

A $60\mathrm{.}0kg$ grindstone is a solid disk $0\mathrm{.}520m$ in diameter.

You press an ax down on the rim with a normal force of

$F=180N($Figure $1).$ The coefficient of kinetic friction

between the blade and the stone is $0\mathrm{.}60,$ and there is a

constant friction torque of $6\mathrm{.}50N*m$ between the axle of

the stone and its bearings.

Figure

How much force must be applied tangentially at the end of a crank handle

$0\mathrm{.}500m$ long to bring the stone from rest to $120re\frac{v}{m}in$ in $7\mathrm{.}00s?$

Express your answer with the appropriate units.

$F_1=,||$

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Part B

After the grindstone attains an angular speed of $120re\frac{v}{m}in,$ what tangential

force at the end of the handle is needed to maintain a constant angular speed of

$120re\frac{v}{m}in?$

Express your answer with the appropriate units.

$F_2=$

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Part C

How much time does it take the grindstone to come from $120re\frac{v}{m}in$ to rest if it

is acted on by the axle friction alone?

Express your answer with the appropriate units.

$t=$

$t=$

$[$