The diagram shows a simplified version of the brake pedal of a car. A driver applies a force of 60N to the pedal. What force is applied to the piston?

Answer:

4) E

This requires the knowledge of moments.

The perpendicular distance from the midpoint of pivot to the midpoint of the pedal = 16 + 4 = 20 cm
Force applied to the pedal = 60 N
Moments = F x d = 60 x 20 = 1200 N cm

The perpendicular distance from the midpoint of pivot to the midpoint of the piston= 4 = 4 cm
Let Force applied to the piston = P
Moments = F x d = P x 4 = 4P N cm

Moment on pedal = Moments on piston

1200 = 4P
P = 1200 ÷ 4 = 300 N