State and explain Newton's first law of motion.

Explanation

Statement : Everybody continues to be in a state of rest or uniform motion along a straight line until an unbalanced force acts on it.
Explanation : `(i)` Consider the mouth of a glass tumbler covered by a thin sheet of paper with a heavy coin on it. When the sheet of paper is pulled suddenly, the coin falls vertically downwards into the glass tumbler due to inertia of position.
`(ii)` Consider a book lying on a table. A force is required in order to cause any linear motion in it. In the absence of an external force, the book continues to occupy that position.