# The Gravitational Constant

Physics

## definition

### Gravitational Constant

The gravitational constant (G) is a proportionality constant that appears in the equation for Newton's law of gravitation. The value of G is approximately equal to

## definition

### Experimental method to determine the value of gravitational constant

The experimental setup performed by Cavendish is shown in the attached figure. Two masses are attached to the end of a horizontal suspended bar. Then, two large lead spheres are brought close to the small ones but on opposite sides. There is no net force on the bar but a non-zero torque acts on it caused due to gravitational force of attraction. This cause twisting of the suspended wire until a maximum angular displacement. At the point of maximum angular displacement, restoring torque is equal and opposite to the gravitational torque.

where is the restoring couple per angle of twist and is constant for a given material.