Projectile Motion
This applet depicts the motion of a basketball as it travels through the air without taking into account the air resistance. We'll consider the motion of the ball after it is projected and before it lands. To put it another way, we're interested in how the ball moves when it's free to move through the air under the influence of gravity alone.
With that in mind, there are two key facts to remember: On the vertical axis, the acceleration is due to gravity, which is constantly pointing downward towards the center of the earth with a magnitude of 9.81 ms-2
On the horizontal axis, there is no acceleration since air resistance is ignored. As a result, the velocity vx in this direction remains constant and equals the initial velocity ux. As a consequence of this, if the ball is launched from a pickup car and the car starts to move at this velocity vx at the same time as the ball is released, the ball will land on the car again.