A student pushes a door that is wide

PHYSICS · Single correct · A Level · Physics · Mechanics and materials · Mechanics and materials

Problem

A student pushes a door that is

0.90\,\text{m}

wide. In which case will the torque about the hinge be zero? (a)

40\,\text{N}

force applied perpendicular to the door

0.30\,\text{m}

from the hinge (b)

40\,\text{N}

force applied at

5^{\circ}

to the plane of the door at its free edge (c)

40\,\text{N}

force applied parallel to the door surface at its free edge (d)

40\,\text{N}

force applied perpendicular to the door at its mid-point