Speed · Usually met around P6
Speed, distance and time
Distance = speed × time.
How to do it
Method
Distance = speed × time
60 km/h for 3 hours: 60 × 3 = 180 km
One more example
180 km at 60 km/h: 180 ÷ 60 = 3 hours
In full
Speed is how far you go in each unit of time. 60 km/h means 60 km every hour, 5 m/s means 5 m every second, and 80 m/min means 80 m every minute. If you know two of distance, speed and time, you can find the third. Distance = speed × time. Speed = distance ÷ time. Time = distance ÷ speed. 60 km/h for 3 hours: 60 × 3 = 180 km. 180 km in 3 hours: 180 ÷ 3 = 60 km/h. 180 km at 60 km/h: 180 ÷ 60 = 3 hours. Match the units: km/h with hours, m/s with seconds and m/min with minutes. If you forget, draw a triangle with distance on top and speed and time below. Cover the one you want, and what's left shows you the sum.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
30 km at 6 km/h = ? h
Show the answer and working
Answer: 30 km at 6 km/h = 5 h
time = distance ÷ speed: 30 ÷ 6 = 5 h
Example 2
60 km/h for 3 h = ? km
Show the answer and working
Answer: 60 km/h for 3 h = 180 km
distance = speed × time: 60 × 3 = 180 km
Example 3
72 km/h for 5 h = ? km
Show the answer and working
Answer: 72 km/h for 5 h = 360 km
distance = speed × time: 72 × 5 = 360 km
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