## Free Fall and Projectiles

Free fall of acceleration

● All objects fall with the same uniform acceleration, because of the gravitational

attraction of earth.

● This acceleration is called acceleration of free fall

● It is presented by g, (9.8 m/s²) and is directed downwards

● In the absence of air resistance, all bodies would fall with the same constant

acceleration

● If body falls from rest, u = 0

● So from the second equation

S = ut + ½ gt²

U = 0

S = ½ gt²

● In free fall, “a = g” and “s = h”

V = u + gt

H = ut + ½ gt²

V² – U² = 2gh

Two dimensional motion

● Motion of a particle moving in two dimensions

● Eg: the motion of a ball thrown at an angle to

the vertical

● Here we consider the vertical and horizontal

components separately

● Throughout the motion, it has an acceleration

of “g” in the “y” direction

● In the horizontal motion (x-direction), the

acceleration is zero, so horizontal component of

velocity remains constant

● The path of particle in the projectile motion is

called parabola

● For a particle projected with a velocity “u” at an angle “θ” to the horizontal

from a point on the level ground

● The range “R” is defined as the distance from the point of projection, the

point at which the particle reaches the ground again

● Equations

- Range “R” = u²sin2θ / g
- Max Height = (usinθ)² / 2g
- Time of flight = 2usinθ / g