A valve handwheel is initially stationary and is free to rotate about its central pivot. No other force produces a moment about the pivot.

Force X is 24 N and has a perpendicular distance of 0.15 m from the pivot. Its moment is clockwise.

Force Y is 15 N and has a perpendicular distance of 0.20 m from the pivot. Its moment is anticlockwise.

The table shows four statements about what happens when both forces are applied at the same time.

Statement	What happens
P	The handwheel starts turning clockwise because the clockwise moment is 3.6 Nm and the anticlockwise moment is 3.0 Nm.
Q	The handwheel starts turning clockwise because the two moments are added to give 6.6 Nm clockwise.
R	The handwheel starts turning anticlockwise because subtracting the two moments gives 0.6 Nm anticlockwise.
S	The handwheel starts turning clockwise because subtracting the forces and the distances gives a moment of 0.45 Nm.

Which statement is correct?

A valve handwheel is initially stationary and is free to rotate about its central pivot. No other force produces a moment about the pivot.

Force X is 24 N and has a perpendicular distance of 0.15 m from the pivot. Its moment is clockwise.

Force Y is 15 N and has a perpendicular distance of 0.20 m from the pivot. Its moment is anticlockwise.

The table shows four statements about what happens when both forces are applied at the same time.

Statement	What happens
P	The handwheel starts turning clockwise because the clockwise moment is 3.6 Nm and the anticlockwise moment is 3.0 Nm.
Q	The handwheel starts turning clockwise because the two moments are added to give 6.6 Nm clockwise.
R	The handwheel starts turning anticlockwise because subtracting the two moments gives 0.6 Nm anticlockwise.
S	The handwheel starts turning clockwise because subtracting the forces and the distances gives a moment of 0.45 Nm.

Which statement is correct?

5.4 Moments, levers and gears

5.4 Moments, levers and gears Questions