## Velocity

Rate of change of displacement with respect to the time is called velocity.

The velocity $$\vec{v}$$ of a particle is given by the following formula,
$$\vec{v} = \frac{\vec{x}}{t}$$
where,
$$\vec{x}$$ = displacement of a particle
t = time taken

Velocity is a vector quantity. SI unit of velocity is metre/second and its dimensional formula is [ M0L 1T-1 ].

## Acceleration

The acceleration $$\vec{a}$$ of a particle is given by the following formula,
$$\vec{a} = \frac{\vec{v}}{t}$$
where,
$$\vec{v}$$ = velocity of the particle.
t = time taken.

Acceleration is a vector quantity. SI unit of acceleration is metre/second2 and its dimensional formula is [ M0L1T-2 ].

## Relative velocity

The velocity of object 2 relaive to object 1 is given by,
v21 = v2 – v1

The velocity of object 1 relaive to object 2 is given by,
v12 = v1 – v2

## Projectile motion

When a body is thrown at some initial velocity, it starts moving along the parabolic path under the influence of gravitational force. This motion in a parabolic path is called Projectile Motion and the desired object is called projectile.