Principle of Moments

Anticlockwise winsThe left-hand turning effect is greater.

Compare both sides

m_1 g d_1 = m_2 g d_2 \Rightarrow 7.85 = 3.92

Anticlockwise7.85 N·m

Clockwise3.92 N·m

Net moment3.92 N·m

DirectionAnticlockwise

Left mass2 kg

Left distance0.4 m

Right mass2 kg

Right distance0.2 m

Try balanced arrangements

Momentforce × perpendicular distance from the pivot

At balancetotal anticlockwise moment = total clockwise moment

Moment values and the balance condition are quantitative. Tilt speed and angle only show the direction and relative size of the imbalance; they do not model rotational acceleration or inertia.

Make the beam tip clockwise
Balance the beam
Hold up a 2 kg mass at 40 cm using a 4 kg mass — where must it hang?
Produce a clockwise moment of about 12 N·m