A mechanic uses a -long wrench to loosen a rusted bolt

PHYSICS · Single correct · A Level · Physics · Engineering physics · Engineering physics

Problem

A mechanic uses a

0.25\,\text{m}

-long wrench to loosen a rusted bolt. The rust produces a resisting torque of

12\,\text{N}\!\cdot\!\text{m}

opposing the wrench’s rotation. The mechanic wants the bolt to start from rest with an angular acceleration of

20\,\text{rad}\,\text{s}^{-2}

. The bolt head can be modeled as a uniform solid cylinder of mass

0.050\,\text{kg}

and radius

8.0\times10^{-3}\,\text{m}

. Neglecting any other torques, what minimum tangential force must the mechanic exert at the end of the wrench? (a)

1.9\times10^{2}\,\text{N}

(b)

4.8\times10^{1}\,\text{N}

(c)

1.2\times10^{1}\,\text{N}

(d)

9.6\times10^{1}\,\text{N}