Any Object that is given an initial velocity at any angle and that subsequently follows a path determined by gravitational force path determined by gravitational force acting on it is called a PROJECTILE

• We started off with a bunch of discarded

wood, some pieces of steel and lots of old

and rusted nails.

• Out of this we built a nice looking launch • Out of this we built a nice looking launch

pad with adjustable angle, an attached

elastic to adjust speed, and a rocket-like

projectile to give the “Effect”!!

Angle (deg) Velocity (m/s) Range (mtr.)

30 9.1 7.4

We launched projectile at different angles and

velocities. The observations are given on next slide

30 4.56 1.95

45 4.56 2.3

45 6.82 4.9

60 4.56 1.8

• The projectile has both a vertical and horizontal components The projectile has both a vertical and horizontal components The projectile has both a vertical and horizontal components The projectile has both a vertical and horizontal components

of velocityof velocityof velocityof velocity

• The only force acting on the projectile once it is shot is gravity The only force acting on the projectile once it is shot is gravity The only force acting on the projectile once it is shot is gravity The only force acting on the projectile once it is shot is gravity

(neglecting air resistance)(neglecting air resistance)(neglecting air resistance)(neglecting air resistance)

• At all times the acceleration of the projectile is g = 10 m/sAt all times the acceleration of the projectile is g = 10 m/sAt all times the acceleration of the projectile is g = 10 m/sAt all times the acceleration of the projectile is g = 10 m/s2 2 2 2 • At all times the acceleration of the projectile is g = 10 m/sAt all times the acceleration of the projectile is g = 10 m/sAt all times the acceleration of the projectile is g = 10 m/sAt all times the acceleration of the projectile is g = 10 m/s

downwarddownwarddownwarddownward

• The horizontal velocity of the projectile does not change The horizontal velocity of the projectile does not change The horizontal velocity of the projectile does not change The horizontal velocity of the projectile does not change

throughout the paththroughout the paththroughout the paththroughout the path

• The Vertical velocity of the projectile reduces on its upward The Vertical velocity of the projectile reduces on its upward The Vertical velocity of the projectile reduces on its upward The Vertical velocity of the projectile reduces on its upward

path and increases in the opposite direction on its downward path and increases in the opposite direction on its downward path and increases in the opposite direction on its downward path and increases in the opposite direction on its downward

pathpathpathpath

ANGLE

� Height increases with increase in Angle.

� Range increases till 45deg. and there on � Range increases till 45deg. and there on

decreases.

(NOTE: 0 < = Angle < = 90)

� Range is same in case of complementary

angles

INITIAL VELOCITY

� Range increases with increase in Velocity.

� Height increases with increase in Velocity.� Height increases with increase in Velocity.

� At the maximum height the vertical velocity is 0.

GRAVITY

� Maximum Height of the projectile is inversely

Proportional to Gravitational AccelerationProportional to Gravitational Acceleration

� Time of Flight is inversely Proportional to

Gravitational Acceleration.

� Range is inversely Proportional to Gravitational

Acceleration.

DRAG

� Increase in Drag Co efficient decreases the range.

� Increase in Drag Co efficient decreases the height.� Increase in Drag Co efficient decreases the height.

� The trajectory of the projectile doesn’t remain

parabolic.

• We can see that the horizontal and vertical motions are independent

• The red ball falls vertically• The red ball falls vertically

• The yellow ball was given a kick to the right.

• They track each other vertically step for step and hit the ground at the same time

To verify that horizontal velocity

is constant in projectile motion we is constant in projectile motion we

shot a video of a ball in projectile

motion, and….

The video was separated into frames

as follows

In the previous six frames, the values for distance covered (x) in regular

intervals of time (t) were recorded as follows:

Distance Covered

(grid units)

Time(s)

From To

1.5 0 0.5

1.75 0.5 11.75 0.5 1

1.5 1 1.5

1.5 1.5 2

1.25 2 2.5

The constant horizontal velocity hence measured is 3 grid

units per second, i.e. constant velocity.