Key Stage 3
Meaning
Speed is how fast something is moving, measured in metres per second.
About Speed
- The scientific units of speed are Metres per Second.
- Speed is commonly measured in the units of Miles per Hour, but this is not a scientific unit.
- Other units of speed can be given by the units of distance used and the units of time used in the calculation of speed.
- Speed can be found by measuring the distance travelled by an object in a given time.
Equation
\[Speed = {\tfrac{distance}{time}} \] \[s = {\tfrac{D}{t}} \] Where:
- s = Speed
- D = Distance
- t = Time
Example Calculations
A person jogs 300 metres in 120 seconds. Calculate the speed of the jogger. | A racing car travels 500 metres in 10 seconds. Calculate the speed of the racing car. |
distance = 300m time = 120s \(Speed = {\tfrac{distance}{time}} \) \(Speed = {\tfrac{300}{120}} \) \(Speed = 2.5m/s \) |
distance = 500m time = 10s \(Speed = {\tfrac{distance}{time}} \) \(Speed = {\tfrac{500}{10}} \) \(Speed = 50m/s \) |
A horse takes 20 minutes to trot 2.4 kilometres. Calculate the speed of the horse in metres per second. | The International Space Station takes 92 minutes to orbit the Earth once travelling 42,000 kilometres. Calculate the speed of the ISS. |
\(Speed = {\tfrac{distance}{time}} \) \(Speed = {\tfrac{2400}{1200}} \) \(Speed = 2m/s \) |
distance = 42,000km = 42,000,000m \(Speed = {\tfrac{distance}{time}} \) \(Speed = {\tfrac{42000000}{5400}} \) \(Speed = 7608.7m/s \) \(Speed \approx 7600m/s \) |