A metre scale is pivoted at its mark

PHYSICS · Subjective · A Level · Physics · Mechanics and materials · Mechanics and materials

Problem

A metre scale is pivoted at its

20\,\text{cm}

mark. A downward force of

5.0\,\text{N}

is applied at the

0\,\text{cm}

mark and an upward force of

3.0\,\text{N}

is applied at the

90\,\text{cm}

mark. (a) Find the magnitude and direction (upward or downward) of a third force that must be applied at the

60\,\text{cm}

mark so that the net torque about the pivot is zero. (b) After this force is applied, what will be the net force acting on the scale?