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Speed Calculations

When a person, car or object moves, you can calculate its average speed if you know how far it has travelled, and how long it took by using the following calculation:

average speed = distance (m) time taken (s)

For example, a person runs 5 km in 25 minutes. This person's average speed in m/s is:

average speed = 5 km x 1000 m /km 25 min x 60 sec/min

= 5000 m 1500 s

= 3.3 m/s

This person's average speed in km/hr is: average speed = 5 km 25 min ÷ 1 hr/60 min

= 5 km 0.4167 hr

= 12.0 km/hr

This person's average speed in miles/hr is: average speed = 5 km x 0.621 mi / 1km

25 min ÷ 1 hr/60 min

= 3.11 mi 0.4167 hr

= 7.46 mi/hr

Below are some simple calculation exercises for you to work through in your own time; you can choose to give your answer in m/s, km/hr or mi/hr. The answers are on the following page for you to check against.

1. A person bicycles 32 km in 45 minutes. What is their average speed?

2. A person runs 15 km in 90 minutes. What is their average speed?

3. A car travels 67 km in 55 minutes. What is the average speed of the journey?

4. A person runs 3km in 17 minutes. What is their average speed?

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ANSWERS BELOW:

1. 42.7 km/hr, 11.9 m/s, 26.5 mi/hr

2. 10.0 km/hr, 2.8 m/s, 6.2 mi/hr

3. 73.1 km/hr, 20.3 m/s, 45.4 mi/hr

4. 10.6 km/hr, 2.9 m/s, 6.6 mi/hr