Question

Define 1st law of motion in class 9

Answer 1

Answer:

Force is the cause whose effect is acceleration.

Explanation:

NEWTON'S FIRST LAW OF MOTION:

Newton's first law defines force.Force is the cause which results in acceleration.

It is also known as galelio,s law of inertia.

Inertia is that ability of a object which prevents it from changing its state of motion.Inertia is of three types....

1. Inertia of rest

2. Inertia of motion

3. Inertia of direction

Answer 2

Answer:

Newton’s first law states that

A body remains in the state of rest or uniform motion in a straight line unless and until an external force acts on it.

Putting Newton’s 1st law of motion in simple words, a body will not start moving until and unless an external force acts on it. Once it is set in motion, it will not stop or change its velocity until and unless some force acts upon it once more. The first law of motion is sometimes also known as the law of inertia.

There are two conditions on which the 1st law of motion is dependent:

Objects at rest: When an object is at rest velocity (v= 0) and acceleration (a = 0) are zero. Therefore, the object continues to be at rest.

Objects in motion: When an object is in motion, velocity is not equal to zero (v ≠ 0) while acceleration (a = 0) is equal to zero. Therefore, the object will continue to be in motion with constant velocity and in the same direction.

Explanation: