# Kinematics

- Created by: Jane
- Created on: 07-04-13 20:50

First 230 words of the document:

Kinematics:

Displacement is the shortest distance from an initial position to a final position, it is a vector a

quantity and so has both magnitude and direction.

Instantaneous speed is the speed of a body at a particular instant in time.

Average speed is a measure of the distance travelled by a body in a given period of time; it is

sometimes referred to as the distance per time ratio. It is a scalar quantity.

Velocity is speed in a given direction; it is defined as the ratio of change in displacement and time

taken. It is a vector quantity.

Acceleration is defined at the ratio of change in velocity and time taken. It is a vector quantity and so

has a direction associated with it. When the velocity of an object increases the change in speed is

positive and the acceleration is positive whereas when the velocity decreases the change in speed is

negative and the acceleration is negative.

Distance-time graphs:

The gradient of the line at any point gives the speed of an

object

Displacement-time graphs:

This shows the displacement of a ball being thrown in the

air.

Displacement (unlike distance) can increase or decrease.

The gradient of the line gives the magnitude of the

velocity.

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