Newtons law of Motion concept and definition of newtons 1,2 & 3 Law

Jul 25, 2022, 16:45 IST

About NEWTONS LAW

Newtons law of Motion concept and definition of newtons 1,2 & 3 Law

NEWTON’S FIRST LAW

When there is no net force on an object an object at rest remains at rest, and an object in motion continues to move with a velocity that is constant in magnitude and direction.

Points to be understand

1.Newton’s first law really describes a reference frame. The property of the body to remain at rest or to retain its uniform linear motion in the absence of applied force is called inertia. The first law is often called the law of inertia and the reference frame to which it applies are termed as inertial reference frames. Thus an inertial reference frame is one which is either at rest or moves with a constant velocity relative to earth. Truly speaking, the earth itself is not an inertial reference frame (because it rotates as well as moves round the sun in an orbit) but for most practical purposes we can treat it as an inertial reference frame.

2.This law does not differentiate between objects at rest and objects moving with constant velocity. Indeed, an object moving with constant velocity in one inertial reference frame can be at rest in another inertial reference frame.

3.No net force here may mean the absence of all forces or the presence of forces whose resultant is zero.

NEWTON’S SECOND LAW

We know from the first law, what happens when there is no unbalanced force on an object: its velocity remains constant. Now let us see What happens when there is an unbalance force on an object ? The Newton’s second Law gives answer to this question, that is, net force acting on a body will produce an acceleration.

When there is a constant unbalanced force on an object, the object moves with constant acceleration. Furthermore, if the force varies, the acceleration varies in direct proportion with the force. Larger force producing larger acceleration. Twice the force produces twice the acceleration in the same mass.