# Newton’s First Law Of Motion ## Newton’s Law Of Motion

Sir Isaac Newton (1642-1727) made a systematic study of motion and extends the views of Galileo. He arrived three laws of motion which are called Newton’s Law of Motion. These laws are as follows.

### Newton’s First Law Of Motion

This law state that every body continuous in its state of rest or of uniform motion in a state line unless it is compelled by some external force to change that state.

The Newton’s first law is categorised in three parts.

##### (I) First Part

If a body at rest, continues in its state of rest. An external force has to be applied on it to make it move.

Example: A book lying on a table.

##### (II) Second Part

If a body is in motion, it continues moving in a straight path with a uniform speed, unless an external force is applied.

Example: A moving ball roll on a straight line.

##### (III) Third Part

If a body moving with a uniform speed in a straight line, cannot change itself its direction of motion.

Example: To change its direction of motion, a force has to be applied normal to this direction of motion.

The motion of moon around the earth.

Note: Newton’s first law defines the law of inertia.