Motion
If the position of an object does not change with time, it is said to be at rest.
If the position of an object changes as time passes, it is said to be in motion.
Reference point is a fixed point with respect of which a body is at rest or in motion.
Rest and Motion are relative terms.
Distance is the length of actual path traveled by a body in a given time.
Displacement is the shortest distance between the initial and final positions of the body in a known direction.
A physical quantity which has both magnitude and direction is called as vector quantity.
A physical quantity which has only magnitude is called as scalar quantity.
The S.I unit of distance and displacement is metre.
A body is said to be in uniform motion, if travels equal distances in equal intervals of time.
A body is said to have non-uniform motion if it travels unequal distances in equal intervals of time.
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NCERT 9 Science