Newton's Laws of Motions

Newton gave three laws governing the motion of the bodies:-

1.       First Law: A body continues to be in its state of rest or uniform motion along a straight line, unless it is acted upon by some external force to change the state.

2.       Second Law: The rate of change of linear momentum of a body is directly proportional to the external force applied on the body, and this change takes place in the direction of the force applied.

3.       Third Law: To every action, there is always an equal and opposite reaction.

NEWTON’S FIRST LAW OF MOTION OR LAW OF INERTIA:

• If the net external force on the body is zero, its acceleration is zero. Acceleration can be non-zero only if there is a net external force on the body.

Inertia: Inability of a body to change its state of rest or state of uniform m otion along a staright line is called inertia of the body.

NEWTON’S SECOND LAW OF MOTION AND LINEAR MOMENTUM:

• Linear Momentum: The product of mass and velocity for moving body is known as momentum. It is a vector quantity whose direction is same as that of velocity and is denoted by P.

Momentum=mass × velocity (Kg m/s)

 P = mv

 The rate of change of linear momentum of a body is directly proportional to the external force applied on the body, and this change takes place in the direction of the force applied.

Since mass is constant, (). We can therefore write the following:

• F= MA

NEWTON’S THIRD LAW OF MOTION:

Force never occurs singly in nature. Forces always occur in pairs as a result of mutual interation betwwen two bodies.

1.     A single isolated force is an impossibility
2.   The two forces involved in any interaction between the two bodies are often called as action and reaction pairs.

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ACTION REACTION PAIR

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