# Net Force Formula

The net force is defined as is the sum of all the forces acting on an object. Net force can accelerate a mass. Some other force acts on a body either at rest or motion. The net force is a term used in a system when there is a significant number of forces. Â

## Formula of Net Force

If N is the number of forces acting on a body, the net force formula is given by,

FNet = F1 + F2 + F3â€¦.+ FN

Where,

F1, F2, F3…FN is the force acting on a body.

Net force when a body is at rest:

When the body is at rest, the net force formula is given by,

FNet = Fa + Fg.

Where,

Fa = applied force,

Fg = gravitational force.
Net force when a body is in motion:

When a force is applied to the body, not only is the applied force acting, there are many other forces like gravitational force Â Fg, frictional force Ff and the normal force that balances the other force.

Therefore, the net force formula is given by,

FNet = Fa + Fg + Ff + FN.

Where,

• FaÂ is applied force,
• FgÂ is the gravitational force,
• FfÂ is the frictional force,
• FNÂ is a normal force.

### Examples of Net Force

Example 1

In a tug of war, a fat man pulls with a force of 100 N on a side, and a lean man pulls with 90 N on the other side. Determine the net force.

Solution:

Given:

Force F1= 100 N

Force F2 = -90 N

The net force formula is given by

FNet = F1 + F2

FNetÂ  = 100 – 90

FNetÂ  = 10 N

Therefore, the net force is 10 N.

Example 2

A toy car is at rest, and a force of 70 N is applied to it. If the frictional force of 20 N, determine the net force.

Solution:

Given:

Applied force Fa = 70 N

Frictional force Ff = -20 N

The net force formula is given by

FNet = Fa + Ff

Â FNetÂ = 70 – 20

FNetÂ  = 50 N

Therefore, the net force is 50 N