How to calculate speed, distance and time using a bar model

Part ofMathsDistance, speed and time

Key points

  • If two of the three variables , distance or time are known, the third can be worked out.

  • A is one way to decide what calculation is needed to solve a speed, distance and time problem. Multiplication and division skills are useful when solving speed, distance and time problems.

It may be useful to review how to calculate speed, distance and time.

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Drawing a bar model to help work out the distance travelled

A can be used as a way of understanding speed, distance and time calculations.

  • The total length of the bar represents both the total distance and the total time taken.

  • The bar is divided into parts. Each part represents the speed as a distance per unit of time.

  • The number of parts gives the number of units of time.

Once the bar is drawn, use the bar model to help with the calculation. To work out distance, multiply speed by time.

Examples

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  1. A bar split into six blocks. The first block is highlighted orange and labelled ‘twenty kilometres per hour’. Above the bar is question mark km; below the bar six hours – both with arrows pointing to each end.

    A bar model can represent speed, distance and time.

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Drawing a bar model to work out speed or time

Bar models can be used to work out speed and time.

Remember:

  • The total length of the bar represents both the total distance and the total time taken.

  • The bar is divided into parts. Each part represents the speed as a distance per unit of time.

  • The number of parts gives the number of units of time.

To work out the speed, divide distance by time.

To work out the time, divide distance by speed.

Examples

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  1. Example 1: Distance equals one-hundred and eighty miles. Time equals three hours. Speed equals question mark – highlighted.

    Work out the speed of an object that travels 180 miles in 3 hours.

Question

How far does a lorry travel if it is driven at an average speed of 54 mph for 3 hours?

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Practise calculating distance, speed and time using a bar model

Practise calculating distance, speed and time using bar models. You might need a pen and paper to help with your answers.

Quiz

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