Newtons Law of Motion


 
 
Concept Explanation
 

Newtons Law of Motion

From the Galileo's experiment we have inferred that

1. If a body is at rest and no external unbalanced force is applied the body will remain at rest.

2. If a body is in motion and no external unbalanced force is applied the body will remain in motion.

3. If an unbalanced force acts on a body its velocity will change.

These ideas we formulated into laws by Newton. Newton's laws of motion are three physical laws that, together, laid the foundation for explanation of motion. They describe the relationship between a body and the forces acting upon it, and its motion in response to those forces. There are three laws of motion:

Newton's First Law of the Motion

A body at rest will remain at rest and a body in motion will remain in uniform motion along a straight line unless an external unbalanced force is applied on it. This law is also called  law of inertia.

Examples

(i) When a carpet or a blanket is beaten with a stick then the dust particles separate out from it.

(ii) If a moving vehicle suddenly stops then the passengers inside the vehicle bend forward.

Newton's Second Law of Motion:

The rate of change of linear momentum is proportional to the applied force and change in momentum takes place in the direction of the applied force.

Examples: 

(i) It is easier for a strong adult to push a full shopping cart than it is for baby to push the same cart.

(ii) It is easier for a person to push an empty shopping cart than a loaded one.

Newton's Third Law of Motion:

The third law says that forces always exist in action reaction pairs. For any force exerted by one body on the other, the second body exerts an equal and opposite force called reaction on the first body.. So the law states that

For every action there is equal and opposite reaction and both acts on two different bodies.

Mathematically    F_{12}:=-:F_{21}

Examples:

(i) Swimming becomes possible because of the third law of motion.

(ii) Jumping of a man from a boat on to the bank of a river.

Sample Questions
(More Questions for each concept available in Login)
Question : 1

When a carpet or a blanket is beaten with a stick then the dust particles separate out from it. It is an example of which law of motion ?

Right Option : D
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Explanation
Question : 2

Who provided a basis for the study of dynamics?

Right Option : B
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Explanation
 
 
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