Torque Equilibrium Example

For an extended system to be at equilibrium, the sum of the torques must be equal to zero. Assuming that the beam is supported under its center of mass, it will contribute no torque. The torque equation in terms of the weights is then

m1 = kg, L1 = m m2 = kg, L2 = m m3 = kg, L3 = m

mass 1 x length 1 + mass 2 x length 2 = mass 3 x length 3

The second equation above is obtained by dividing through by g. Since g appears in every term, it can be factored out and just the products of masses and lever arms used.