Physics

Problem

For a torsion-spring system the torque on a vane is modeled by

\tau=-k\sin(2\theta)

, where

\theta

is measured in degrees from a reference line. Which of the following sets lists all angular positions between

0^{\circ}

and

180^{\circ}

at which the vane is in rotational equilibrium? a)

45^{\circ}\text{ and }135^{\circ}

0^{\circ}\text{ and }180^{\circ}

0^{\circ},\,90^{\circ},\,180^{\circ}

90^{\circ}\text{ only}