Section A - Distance, Displacement, Velocity and Acceleration, Equation of Motion


* An object is said to be in motion wrt a frame of reference S1, when its location is changing with time in same frame of reference S1.

* Rest and motion are relative terms.

* Absolute rest and absolute motion have no meaning.

Motion is broadly classified into 3 categories.

1. Rectilinear and translatory motion.

2. Circular and rotatory motion.

3. Oscillatory and vibratory motion.

1.1 Rectilinear or 1-D Motion

When a particle is moving along a straight line, then its motion is a rectilinear motion.

Parameters of rectilinear motion or translatory motion or plane motion:

(A) Time :

* It is a scalar quantity and its SI unit is second(s).

* At a particular instant of time, a physical object can be present at one location only.

* Time can never decrease.

(B) Position or location - It is defined with respect to some reference point (origin) of given frame of reference.

Consider a particle which moves from location

(at time t1)

to location

(at time t2) as shown in the figure below, following path ACB.

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