Any object that moves horizontally through the air as well as vertically because of the effects of gravity is a called a projectile. A projectile is an object moving under the influence of gravity.
The force of gravity produces the same downward acceleration on all objects. Any mass (a 1kg mass or a 10kg mass) will accelerate downwards at 9.8ms^-2
Some projectiles only move vertically. Other projectiles move horizontally and vertically at the same time. When we investigate the motion of a projectile, the horizontal and vertical motion of the projectile are kept separate.
Horizontal MotionThe horizontal speed of a projectile is constant for the duration of its flight. This is because, once launched, there are no horizontal forces acting on the projectile (air resistance is usually ignored because it is very small) so horizontally the projectile wil travel at a constant speed.
For any calculationsinvolving the projectile's horizontal motion, we use:
distance = speed x time
The vertical motion of a projectile is controlled by the force of gravity…