2. What is Projectile motion?
Projectile motion is the type of motion of
an object under the force of gravity
Example: Throwing a ball in the air at any
angle the ball follows a projectile motion
The image shows projectile motion as
followed by a ball
The path of projectile motion is a parabola
2
2 8
1 9
6
3
4
5
7
3. Breaking up projectile motion
Important :
Projectile motion is just a combination of motion in 2 directions at
the same time
Motion in Horizontal direction (X-direction)
Motion in Vertical direction (Y-direction)
When the above two motions occur at the same time, it is called
PROJECTILE MOTION
To understand and solve projectile motion problems, it is useful to
break it up into separate horizontal and vertical components
3
4. Motion in Horizontal direction (X-
direction)
Motion in horizontal or x-direction is just straight line motion, hence we
do not need to consider any vertical component or vertical motion
We do not have any horizontal acceleration, only velocity is present in
horizontal direction in case of projectile motion
Formula to use:
Velocity (in x-direction) = Distance/Time
4
5. Motion in Vertical direction (Y-direction)
Motion in vertical or y-direction is also a straight line motion, hence we do not
need to consider any horizontal component or horizontal motion
Acceleration due to gravity (g=9.8m/s2) is present in the vertical direction
directed downwards (towards the earth)
Newton’s equations of motion (for motion under acceleration) are required:
Important Equations (Remember / Memorise)
v = u + a*t …1
s = u*t+(1/2)*a*t2 …2
v2 = u2 + 2*a*h …3
Here,
s – distance covered; u – initial velocity; v – final velocity
t – time duration of the motion; a – acceleration acting on the object;
5
6. Sign Convention and Directions
For Horizontal Motion
If motion is to the right (+ve x-direction), velocity is considered +ve
If motion is to the left (-ve x-direction), velocity is considered –ve
For Vertical Motion
The direction of velocity and acceleration are completely independent of
each other.
Direction of acceleration is where the object is being pulled (or pushed)
Example: downward (-ve) acceleration in case of acceleration due to gravity,
hence a = -9.8m/s2, as the object is pulled downward due to gravity
6
