Force as the Cause of Change in Motion
Force is the cause of change in motion or change in the state of motion. When an external force is applied to an object, it can either start moving, stop moving, or change its direction and speed. This is explained by Newton's first law of motion which states that an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

Explanation:
- Definition of Force: Force is a push or pull acting upon an object as a result of its interaction with another object. It is a vector quantity, meaning it has both magnitude and direction.
- Newton's Second Law of Motion: This law states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. Mathematically, it can be represented as F = ma, where F is the force applied, m is the mass of the object, and a is the acceleration produced.
- Types of Forces: There are different types of forces such as gravitational force, frictional force, normal force, tension force, applied force, and spring force. Each of these forces can cause a change in the motion of an object.
- Examples: For example, when a football player kicks a ball, the force applied by the foot causes the ball to move. Similarly, when a car applies brakes, the force of friction between the tires and the road causes the car to stop.
- Resultant Force: When multiple forces act on an object, the resultant force is calculated by adding or subtracting the individual forces. The direction of the resultant force determines the direction of the motion change.
In conclusion, force is the fundamental cause of any change in motion or state of motion. Understanding the concept of force is essential in explaining various phenomena in physics and everyday life.