Part A

A $70\mathrm{.}0kg$ grindstone is a solid disk $0\mathrm{.}570m$ 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

$1$ of $1$

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 $8\mathrm{.}00s?$

Express your answer with the appropriate units.

$F_1=$

Request Answer

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.

$F_2=$