Concepts of Physics

IIT JEE Physics (1978-2018: 41 Years) Topic-wise Complete Solutions

The Physics of the Beam Balance


To study the physics of balance


For a body to be in equilibrium, the net force and net torque should be zero. The setup consists of a scale hinged at its middle point. The scale has holes at regular interval to hang weights at different distances from the hinge point.


slotted weights, thread, setup with scale



  • Check that scale is almost balanced. If not, fix a suitable weight to balance it.
  • Attach a fixed weight at one end of the scale.
  • Attach another weight on other side of hinge point so that scale is balanced.
  • Repeat above step for different weights.
  • Verify that net force on the scale and net torque about the hinge point is zero in balanced condition.


According to lever principle, a smaller force applied at a greater distance from the axis of rotation can lift a larger weight.