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.