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4.10 J) Speed – Part 2

4.10 J) Speed – Part 2

The formula for speed, distance and time is shown below:

We are going to be looking at more complex questions in this section. Before you work through this section, make sure that you have covered the content in the previous section (click here to be taken through to the previous section).

**Example 1**

You can use a calculator for the following question.

It takes a runner 16 minutes to run 3,000 m.

a) Work out the speed of the runner in metres per seconds (m/s).

b) Work out the speed of the runner in in kph.

Both of the questions are asking us to work out the speed of the runner. We are able to find the calculation that we need by using the formula triangle and covering up s. The formula triangle is shown below:

When we cover s, we see that the calculation that we need to undertake is:

We will be using this calculation to answer part a and part b.

Part a asks us to work out the speed of the runner in metres per second. This means that the distance in the formula needs to be measured in metres and the time needs to be measured in seconds.

We are told in the question that the distance is 3,000 m. This is in the correct units, which means that we can sub the distance into the formula.

**Part a**Part a asks us to work out the speed of the runner in metres per second. This means that the distance in the formula needs to be measured in metres and the time needs to be measured in seconds.

We are told in the question that the distance is 3,000 m. This is in the correct units, which means that we can sub the distance into the formula.

We are also told in the question that the time is 16 minutes. We need to have the time in seconds. There are 60 seconds in a minute, which means that we can convert 16 minutes into seconds by multiplying by 60.This means that the calculation for working out the speed in metres per second is:

The speed of the runner is 3.125 m/s.

Part b asks us to work out the speed in kilometres per hour. This means that we need to ensure that the distance is in kilometres and the time is measured in hours.

We are told in the original question that the distance is 3,000 m. There are 1,000 m in a kilometre, which means that we can convert the 3,000 metres into kilometres by dividing by 1,000. The numerator of the calculation is shown below:

**Part b**Part b asks us to work out the speed in kilometres per hour. This means that we need to ensure that the distance is in kilometres and the time is measured in hours.

We are told in the original question that the distance is 3,000 m. There are 1,000 m in a kilometre, which means that we can convert the 3,000 metres into kilometres by dividing by 1,000. The numerator of the calculation is shown below:

We are told in the original question that the time is 16 minutes and we need to convert this time into hours. There are 60 minutes in an hour, which means that we convert 16 minutes into hours by dividing by 60. This means that the denominator of the calculation becomes:

The final step is to type this into a calculator.

The speed of the runner is 11.25 kph.