9.) State Newton's first law of motion.
Answers
His first law states that every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force. This is normally taken as the definition of inertia.
Newton's First Law of Motion :
A body at rest will remain at rest,and a body in motion will remain at motion in a straight line with a uniform speed,unless it is compelled by an external force to change its state of rest or of uniform motion.
Example :
Suppose a book is lying on the table. It is at rest. The book will not move by itself,it cannot change its position of rest by itself. It can change its state of rest only when compelled by the force of our hands,that is,when we left the book from the table. Thus,the position of rest of the book has been changed by the external force of hands.
Other Details :
Newton's Second Law of Motion :
The rate of change of momentum is directly proportional to the applied force,and takes place in the direction in which the force acts.
Newton's Third Law of Motion :
To every action there is an equal and opposite reaction.