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## Key Concepts

• Net force
• Balanced force
• Unbalanced force

## Introduction:

In a tug of war, the one applying more force wins the game. In this session, we will calculate this force that makes one team win and one team lose. We will learn about it in terms of balanced force and unbalanced force.

## Explanation:

### Force

Force is an external effort that may move a body at rest or stop a moving body or change the speed of a moving body or change the direction of a moving body or change the shape and size of a body.

• It is a vector quantity.
• It is the push or a pull on an object resulting because of the object’s interaction with another object.
• It is measured in units called Newtons (N).

#### Effects of force:

• Force can move a body at rest
• Force can stop a moving body
• Force can change the speed of a moving body
• Force can change the direction of a moving body
• Force can change the shape and size of a body.

### Net force:

The net force is the vector sum of all the forces that act upon an object. Since it is a vector quantity, it has both direction as well as magnitude. The net force based on its magnitude is classified into two types.

### Balanced force:

If two forces act on a body in opposite directions and if both the forces are equal, then the resultant force acting on the body is zero. Such forces are called balanced forces.

• They do not cause any change in the state of an object.
• They are equal in magnitude and opposite in direction.
• They can change the shape and size of an object.
• There is zero acceleration.

### Unbalanced force:

If two forces act on a body in opposite directions and one is greater than the other, then the resultant force acting on the body is not equal to zero. Such forces are called unbalanced forces.

• They cause a change in the speed and position of an object.
• They are not equal in magnitude.
• They cause a change in the shape and the size of an object.
• There is an acceleration of the object
• The direction of the net force is in the direction of the force with a larger magnitude.

Question 1: What is the net force and the direction of the net force?

Question 2: Fill the table.

### Summary

• Force is a vector quantity.
• Force is the push or a pull on an object resulting because of the object’s interaction with another object.
• Force is measured in units called Newtons (N).
• Balanced force
• a. They do not cause any change of state of an object.
• b. They are equal in magnitude and opposite in direction.
• c. They can change the shape and size of an object.
• Unbalanced force
• a. They cause a change in the speed and position of an object.
• b. They are not equal in magnitude.
• c. They cause a change in the shape and the size of an object.

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