 # Work Done By Gravity Formula

## Work Done by Gravity Formula

Gravity is defined as the force that attracts a body towards the earth or towards any other physical body having mass.

If a particular object is falling, the particle is bound to point in the direction of gravity. The magnitude of the falling body depends on the mass, gravitational constant and height from which it is falling.

The Work done by gravity formula is given by,

Wg = -mg(∆ h)

Where,

m = mass,

g = gravity,

h= height

The negative sign shows that the particle is dropping from a height Δ h vertically in the direction of gravity.

If θ is the angle made when the body falls, the work done by gravity is given by,

W = mgh cosθ

Where, the theta is the angle made when the body falls.

Example 1

A 15 kg box falls at angle 25 from a height of 10 m. Determine the work done by gravity.

Solution:

Given:

Mass m = 10 kg,

angle = 23o

The work done by gravity formula is given by,

W = mgh cos θ

W = 15 × 9.8 × 10 cos 25o

=   1470 J

Therefore, the work done by gravity is 1470 J.

Example 2

A boy drags a 10 kg box across frictionless surface. He applies a force of 30 N at an angle of 32o to the horizontal for 6m. Determine the work done by gravity.

Solution:

Given:

Mass m = 10 kg,

Force F = 30 N,

angle θ = 32o,

Displacement s = 6m

The work done by gravity formula is,

W = mgh cos θ

W = 10 x 9.8 x 6 × cos 32o

W = 490.392 J.

the work done by gravity is 490.392 J