Motion under Gravity

Description:

Motion under gravity is accelerated motion and it is known as acceleration due to gravity, it is given by −

g = 9.8 ms^-2

When a body is thrown upwards, it has an acceleration −

a = -g

When a body is dropped, it has an acceleration −

a = g

Acceleration due to gravity is always directed downwards (towards the center of the earth)

Note − Direction towards the center of the earth is known as vertical and direction normal (perpendicular) to vertical is known as horizontal.

We can derive equation for acceleration due to gravity using kinematic equations −

We have kinematic equation −

v = u + at

S = ut + 1/2 at²

2aS = v² - u²

When a particle is thrown upwards −

v = u - gt

h = ut - 1/2 gt²

-2gh = v² - u²

When a particle is dropped −

v = u + gt

h = ut + 1/2 gt²

2gh = v² - u²