First law of motion :
A body continues its state of rest or of uniform motion unless a net force acts on it.
Ex:
- When the bus which is at rest begins to move suddenly, the person standing in the bus falls backward.
- When you are travelling in bus, the sudden stop of the bus makes you fall forward.
Second law of motion :
The rate of change of momentum of a body is directly proportional to the net force acting on it and it takes place in the direction of net force.
Ex :
Place a ball on the veranda and push it gently. Then the ball accelerates from rest. Thus, we can say that force is an action which produces acceleration.
Third law of motion :
If one object exerts a force on the other object, the second object exerts a force on the first one with equal magnitude but in opposite direction.
Ex :
- When birds fly, they push the air downwards with their wings, and the air pushes back the bird in opposite upward direction.
- When a fish swims in water, the fish pushes the water back and the water pushes the fish with equal force but in opposite direction.
- A rocket accelerates by expelling gas at high velocity. The reaction force of the gas on the rocket accelerates the rocket in a direction opposite to the expelled gases.
