Projectile Motion
What is Projectile Motion?
Two-dimensional motion is the motion of a body along a plane. If the motion of the plane is
considered along the XY plane, then the x coordinate and y coordinate of the position of the
particle changes with time. In two-dimensional motion, the body moves along a curved path
instead of a straight path.
The two main examples of two dimensional motion are projectile motion and circular motion.
Projectile Motion of a Body Under Gravity
In Physics, projectile motion is defined as the motion of an object under the influence of gravity.
A body thrown vertically upwards is an example of projectile motion. For projectile motion, the
air resistance acting on the body is neglected and the only force acting on the body is the
gravitational force. A body thrown with an initial velocity at an angle with the horizontal is a
projectile motion.
For a projectile motion, the gravitational force acting on the body is in the downward direction.
Therefore, the body in a projectile motion has acceleration due to gravity 9.8 m/s2. It must be
noted that no force is acting on the body in the projectile motion in the horizontal direction.
Therefore, the acceleration of the body in the horizontal direction is zero. The projectile motion
is uniformly accelerated motion. Therefore, we can apply the equations of motion in the vertical
and horizontal directions.
In this projectile, the path followed by the body is called a trajectory. A ball that is thrown
horizontally from the top of a cliff is also a projectile motion.
Types of Projectile Motion
There are different types of projectile motion based on the direction of the initial velocity of the
projectile. The three main types are:
1. Vertical projectile motion
2. Horizontal projectile motion
3. Oblique projectile
Vertical Projectile Motion
In the vertical projectile motion, the angle between the initial velocity and the horizontal direction
is 90°. The body moves in a vertical direction under the action of gravity. The horizontal initial
velocity (ux) of the projectile is zero and the initial velocity is only along the vertical direction.
Horizontal Projectile Motion
In horizontal projectile motion, the object is thrown in the horizontal direction and the angle
between the initial velocity and the horizontal is zero. Therefore, the initial velocity of the
projectile is along the horizontal direction and the vertical component of the initial velocity of the
horizontal projectile motion is zero. The trajectory of horizontal projectile motion is a parabola.
The body moves in the horizontal direction along with vertical down motion along the parabolic
path.
Oblique Projectile Motion
In oblique projectile motion, the initial velocity of the body is making an angle with the horizontal.
The angle made by the initial velocity with the horizontal is greater than 00 and greater than 90°.
Oblique projectile motion is also called angular projectile motion. The trajectory of angular
projectile motion is a parabolic path.
Vertical Projectile Horizontal Projectile Oblique Projectile
Motion Motion Motion
Maximum height 𝑢2 1
H=2𝑔 H= 2gt2
