Calculating speed, distance and time - KS3 Maths

Key points

We can use formulas to model real-life situations.
For example, the formula for calculating speed is speed = distance ÷ time.
It is possible to calculate the speed, distance or time if you have the other two values.

Video

This video can not be played

To play this video you need to enable JavaScript in your browser.

Discover how to work out the speed of an object

What is speed?

Speed tells us how fast something or someone is travelling. You can find the average speed of an object if you know the distance travelled and the time it took.

The formula for speed is speed = distance ÷ time. To work out what the units are for speed, you need to know the units for distance and time. In this example, distance is in metres (m) and time is in seconds (s), so the units will be in metres per second (m/s).

Calculating speed

Skip image gallery

Image caption,
Click to see a step by step slideshow.
Image caption,
WHAT YOU NEED: A whiteboard, pens, a board rubber and a calculator to check your answers.
Image caption,
STEP 1 - Write the formula Speed = Distance/Time on the board.
Image caption,
STEP 2 - Divide the distance travelled (150 metres) by the time it took to travel (25 seconds).
Image caption,
STEP 3 - Do the calculation 150 divided 25. You can use a calculator if you need to! The answer should be 6.
Image caption,
STEP 4 - Now add the units. Meters are divided by seconds, so the answer is 6 m/s (metres per second). Make sure to always put the units at the end of your answer!