Projectiles
In physics, any object moving freely under gravity is called a projectileAn object flying through space unaided by an engine, eg the cannon shot a projectile over the horizon..
By moving freely it is assumed there is no air resistanceA force of friction produced when an object moves through the air. or other external forces. In practice many sports balls achieve lift due to spin.
The motion of projectiles must be analysed in terms of verticalAt right angles to the ground or horizontal. and horizontalParallel to the ground. components.
Horizontal component
The horizontal component of velocity is constant speedWhen the speed of body does not change, eg the car was travelling at a constant speed of 30 m s-1. (assuming no air resistance).
Projectiles - horizontal motion
Vertical component
The vertical component is accelerationThe rate of change in speed (or velocity) is measured in metres per second squared. Acceleration = change of velocity 梅 time taken. downwards due to gravity (-9.8 ms-2 on Earth)
Projectiles - vertical motion
If the initial velocity is given as a speedThe distance travelled in a fixed time period, usually one second. and directionInformation to give the direction of travel, or the direction of a force, for example, a speed of 20 m s-1 to the left, or a force of 15 N to the right., this velocity vector must be resolved into two components by trigonometry.
The two components can allow the calculation of:
- timeTerm that describes the order and duration of events. For example, the Physics lesson was 50 minutes long. of flight
- maximum height reached
- range 鈥 horizontal distanceNumerical description of how far apart two things are. For example, the distance from Edinburgh to Glasgow is approximately 50 miles. from launch to landing
Watch this video for a practical demonstration of firing a ball obliquely and calculating values related to the horizontal and vertical components of motion.