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In the statement of Newton’s first law, the unbalanced force means the force that does not become balanced by the other individual force. If all the up and down forces do not cancel each other and/or all the horizontal forces do not cancel each other, then there is an unbalanced force. It is commonly accepted that there is the ‘net force’ acting upon the object. The net force is the sum of all forces, considering the fact that a force is a vector and two forces of equal magnitude and opposite direction will cancel each other.

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

FNet = F1 + F2 + F3 ....+ FN

Where F1, F2, F3 as forces acting on a body.

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

FNet = Fa + Fg

Where,

Fa = Applied force and

Fg = Gravitational force.

Net force is when a body is in motion and many forces are active on it like gravitational force F_{g}, frictional force F_{f}, and the normal force.

Therefore, the net force formula is given by

FNet = Fa + Fg + Ff + FN.

Example 1

In a game of rope pulling, a fat man pulls with a force of 100 N from one side, and a lean man pulls with 90 N from the other side. What will be the net force?

Solution:

Given

Force F1 = 100 N and

Force F2 = 90 N

The net force formula is given by

FNet = F1 + F2

FNet = 100 + (-90)

F_{Net} = 10 N.

Therefore, the net force is 10 N.

Example 2

A truck is standing still and a force of 70 N is applied on it. If the frictional force is 20 N, then what will be 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

FNet = 70 + (-20)

FNet = 50 N

Therefore, the net force is 50 N.

FAQ (Frequently Asked Questions)

1. What is net force and how do we calculate it?

The net force is the sum of all the forces that are applied to an object. This means that the net force is the total of all forces, considering the fact that a force is a vector and two forces of opposite direction but with equal magnitude will cancel each other resulting in zero net force.

2. How is a net force calculated?

The net force is calculated as below

F_{Net} = F_{1} + F_{2} + F_{3}....+ F_{N}

Where F_{1}, F_{2}, F_{3} are the number of forces or

F_{Net} = F_{a} + F_{g} + F_{f}

Where

F_{a} = applied force

F_{g} = gravitational force and

F_{f} = frictional force.

3. When the net force on an object is zero?

Newton’s first law states that an object with a net force of zero acting on it remains at rest, if initially at rest, or it will maintain a constant velocity. For the stretched spring to remain motionless it must be given equal and opposite forces from both the ends.