Define projectile and write two examples.

1. A projectile is a body thrown with some initial velocity in the horizontal direction and then allowed to move under the action of gravity alone, without being propelled by any engine or fuel.
2. The gravitational force acts to the maximum extent and the other forces ( like air resistance) are negligible.
3. The path followed by the projectile is called a trajectory.
4. Examples of projectile: A piece of a stone thrown in any direction, a bullet fired from a gun.
5. A projectile moves under the combined effect of two velocities

1. A uniform velocity in the horizontal direction $\left(u\cos \theta \right)$
2. A uniformly changing velocity in the vertical direction due to gravity. $\left(u\sin \theta \right)$