# NEWTON'S LAW OF MOTION ( part 3) " 2nd LAW OF MOTION ( F=ma) "

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Newton gave a mathematical relationship between the applied force on a body, acceleration and mass of the body which is known as Newton’s second law of motion.

## Statement:

It states that “When a net force is applied on a body it produces acceleration in body in the direction of force in such a way that acceleration is directly proportional to the net force and inversely proportional to the mass of the body.”

## Mathematically:

##### F=ma,

Where ‘F’ is net force “m” is mass of the body and “a” is acceleration produced in the body. ## Free falling bodies due to Earth Gravity:

In case of free falling body acceleration due to gravity is “g” (near surface equal to 9.8m/s/s). Gravitational Force acting on the body provides weight to the body. So equation will be W=mg

## IS Newton’s 2nd law of motion contradicts Galileo’s law of free falling bodies:

I have been asked this question to many people in my university and college as well but I observe that mostly people are very clear that Newton and Galileo are not contradicting with each other, but when I asked my next question which is

#### But according to Newton’s second law of motion “acceleration is inversely proportional to the mass of the body.”

I found mostly people confused were about this even in physics groups on Face book also. But it is very interesting that both are not contradicting with each other.

According to Newton’s 2nd law acceleration is inversely proportional to mass of the body” This is only applicable when force acting on the body is kept constant. In case of free falling bodies Gravitational force changes by changing mass but acceleration remain constant which is also according to Newton’s 2nd law of motion.Hence Both are not contradicting.

Force is a vector physical quantity.. In SI units unit of force is ‘Newton’. One Newton is quantity of force which produces acceleration of magnitude 1 m/s if the mass of the body is 1 kg.

From above equation we can find magnitude of force .For example F=ma

F=(2000).(0.0 5) NEwton

F=100 Newton

The End