Physics Complete: Projectile Motion

It is nothing but two dimensional motion.It could be either from ground or from a certain height.If a body is changing its position along X and Y axis with respect to time then it is called projectile motion.

An object that is in flight after being thrown or projected is called a projectile. Such a projectile might be a football, a cricket ball, a baseball or any other object. The motion of a projectile may be thought of as the result of two separate, simultaneously occurring components of motions. One component is along a horizontal direction without any acceleration and the other along the vertical direction with constant acceleration due to the force of gravity.

we shall assume that the air resistance has negligible effect on the motion of the projectile for a simple projectile equation.

Let us assume that the projectile is launched with velocity vo that makes an angle θo with the x-axis as shown in Fig. below.

After the object has been projected, the acceleration acting on it is that due to gravity which is directed vertically downward:

a = −g j which means that
ax = 0, ay = – g
The components of initial velocity vo are :

v along x axis is = vo cos θo
v along y axis is = vo sin θo

If we take the initial position to be the origin of the reference frame as shown in Fig. we have :

One of the components of velocity, i.e. x-component remains constant throughout the motion and only the y- component changes, like an object in free fall in vertical direction. This is shown graphically at few instants in Fig. below Note that at the point of maximum height, vy= 0 and therefore, tan θ = y component of velocity /x component of velocity = 0.