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