Newton gave out three laws which laid the foundation for the classical mechanics. The laws collectively describe the relationship between the body and the forces that act upon it along with its motion in response to the forces.

The first law basically describes the force qualitatively; the second law gives a quantitative measurement of the force; and the third law asserts that there is absence of a single isolated force.

The three laws were compiled by Isaac Newton in 1687. He used them to investigate and explain the motion of varied physical objects and systems.

**THE SECOND LAW**

The second law of motion states that the rate of change of momentum of a body is directly proportional to the force applied and the change in momentum takes place in the direction of the force applied.

This means that the acceleration of an object is dependent on two variables-

- Acceleration of the object is directly proportional to the net force which is acting on the object
- Acceleration of the object is inversely proportional to the mass of the object.

This means that by increasing the force acting on it, the object’s acceleration increases while by increasing the mass results in decreasing the acceleration of the object.

**F= m * a**

Where,

- F is the net force acting on the object,
- M is the mass of the object,
- A is the acceleration of the object. The acceleration is in the same direction as that of the net force since the net force is responsible for producing the acceleration.

One Newton (the standard metric unit of force) is defined as the amount of force which is required by a mass of 1 kg to give an acceleration of 1 m/s/s.

Thus, 1 Newton = 1 KG m/s2

**APPLICATIONS OF NEWTON’S SECOND LAW OF MOTION**

- Newton’s second law of motion applies to the behaviour of the objects for which the existing forces are unbalanced.
- It also establishes the relation between impulse and momentum.
- The law governs the behaviour of everything that can be seen and unseen on the planet Earth and also in the cosmos. It tells the amount of force required to give acceleration to an object.

People try to constantly reduce the mass of objects because they want to increase the speed and acceleration. This concept comes from Newton’s second law. Eg. People with less weight would be able to walk faster than a person with more weight (same force).