Projectile motion is caused by gravity's effect on the path of any object that is launched or thrown, according to HowStuffWorks. Projectile motion has both horizontal and vertical components. The horizontal component is due to the velocity of the object, while the vertical component is due to the force of gravity.Continue Reading
Most projectile-motion problems ignore air resistance on the object. Under this assumption the only force acting on the object is that of gravity once it leaves the hand of the thrower. Inertia continues to carry it at the same velocity horizontally until it hits the ground. However, the force of gravity acting on the object causes it to create a parabolic curve. If a football player throws a pass with an upward motion, the vertical component of the pass slows due to gravity until it reaches zero, and then the ball starts to accelerate as it begins its descent to the ground.
Objects that begin their journey horizontal with the ground also follow a parabolic curve; however, the curve has no upward component, so the curve is one-half of a parabola cut at its vertex. The time for gravity to pull the object to the ground is the same as if someone drops it from the same height. If it has an upward component, the time until it hits the ground is the same as if one throws it upward to the height where it reversed its acceleration.Learn more about Motion & Mechanics