# ^What is a projectile

**^What is a projectile **

A projectiles is any object moving under the influence of gravity. There are several ways to throw a projectile, vertically up, vertically down, horizontally, at some angle up, at some angle down etc.

- Object is thrown
**→**means initial speed non zero. - Object is dropped
**→**means initial speed zero.**Assumptions**Following are few assumptions in the study of projectiles.

- Projection speed u << v
_{ escape}so that g remains constant with the height & equations of UAM can be used to study the problems based on projectiles. - Wind is absent for simplicity of mathematics.
- Air friction is absent if not specified so that the mechanical energy of the projectile remain constant throughout the motion. i.e.

K + U = same at all the points of trajectory.

4. The acceleration of any projectile on earth is a = constant = g = 9.8 m/s

^{2 }= 32 ft/s^{2}directed towards the centre of the earth irrespective of its mass, position, time, speed of projection & angle of projection. As the acceleration of a projectile is ‘g’ acting along – y, thus it has no x & z components. - Projection speed u << v