A mechanic can push at any point on the rim of a horizontal wheel of radius

PHYSICS · Single correct · AP · Physics 1: Algebra-based · Torque and Rotational Dynamics · Torque and Rotational Dynamics

Problem

0.4\,\text{m}

. Owing to space constraints, the magnitude of force he can exert varies with the angle

\theta

(in degrees) between the force and the radius according to

F = 120\cos\theta\,\text{N}

for

0^{\circ} \le \theta \le 90^{\circ}

. Which pair gives the angle that maximises the torque about the axle and the corresponding maximum torque? (a)

60^{\circ}

20.8\,\text{N m}

(b)

45^{\circ}

24\,\text{N m}

(c)

30^{\circ}

24\,\text{N m}

(d)

45^{\circ}

34\,\text{N m}