**Free fall acceleration**

A body falling freely is solely acted by Earth Gravitational force. The falling body is accelerated by the Gravitational force and acceleration due to this gravitational force is called acceleration due to gravity.

Acceleration due to gravity values slightly differs at different altitude and surface .For all practical calculation purpose, we take it approx 9.8 m.s^{-2} or 10m.s^{-2} .Direction is always downwards. It is also denoted by letter **‘g’**.

Freely falling motion of anybody under the effect of gravity is an example of uniformly accelerated motion.

The kinematic equation of motion under gravity can be obtained by replacing acceleration **‘a’** in equations of motion by acceleration due to gravity **‘g’**.

v=u+ gt

v^{2} = (u)^{2} + 2gs

s = ut + ½ (gt^{2})

Where

v=Final Velocity

u=Initial Velocity

g= Constant acceleration

t= time interval

s= displacement

The value of g is taken positive when the body falls vertically downwards and negative when the body is projected up against gravity.

Value of g is equal to 9.8 m.s^{-2}.

**Example -1**

An object dropped from a cliff falls with a constant acceleration of 10 m/s

^{2}. Find its speed 5 s after it was dropped

**Solution**

It is an example of Free Fall acceleration

u=0

t=5 s

g=10

v=?

From

v=u+ gt

=10×5 =50 m/s