The rate of change of displacement - distance in a certain direction - is called the velocity.

Velocity = displacement /time

The **gradient** of a distance time graph is **speed.**

*Units: ms ^{-1}*

The rate of change of velocity - speed in a certain direction - is called the acceleration or deceleration.

Acceleration = velocity / time

The **gradient** of a velocity time graph is **acceleration or deceleration.**

*Units: ms ^{-2}*

The following animation help you distinguish between *displacement* and *distance.*

The following animations show displacement / time graphs and their corresponding velocity / time graphs and acceleration / time graphs.

In the animation, the ball goes up under gravity: the velocity comes down, becomes zero and then increases again, as it comes down. The acceleration remains constant throughout the motion, in the absence of air resistance, also known as drag.

**Practice is the key to mastering physics; please visit this page, for more worksheets.**

Now practise the following to complement what you have learnt so far.

Draw distance-time graphs and corresponding velocity-time graph and acceleration-time graphs for the following:

- A ball dropped from the top of a tower
- A ball dropped from the top of a tower on to a perfectly elastic floor to be bounced back once
- A ball thrown upwards and then catch it again after a while
- The motion of an aircraft on landing after a long journey
- The motion of a parachutist when coming down
- The motion of a feather in the air

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They are organized according to these specific levels.

The major categories are for core mathematics, statistics, mechanics and trigonometry. Under each category, the tutorials are grouped according to the academic level.

This is also an opportunity to pay tribute to the intellectual giants like Newton, Pythagoras and Leibniz, who came up with lots of concepts in maths that we take for granted today - by using them to serve mankind.

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