JAMB - Physics (2003 - No. 9)
A 90cm uniform lever has a load of 30N suspended at 15cm from one of its ends. If the fulcrum is at the center of gravity, the force that must be applied at its other end to keep it in horizontal equilibrium is
15N
20N
30N
60N
Giải thích
∴from the principle of moments,
F x 45 = 30 x 30
∴ F = (30 x 30) / 45 = 20N