Speed and other rates · Grade 8

In Grade 8 you learn: converting units of speed.

A rate compares two different quantities, such as kilometres per hour, litres per minute or words per minute. Speed is the most common rate: it links distance, time and how fast something moves.

Key facts

• Speed = distance ÷ time; distance = speed × time; time = distance ÷ speed.
• For km/h, use the time in hours: 15 min = 0.25 h, 20 min = 1/3 h, 45 min = 0.75 h.
• Average speed = total distance ÷ total time — not the average of the speeds.
• km/h → m/s: ÷ 3.6. m/s → km/h: × 3.6.
• Every rate works the same way: amount = rate × time.

Worked examples

Other years

• Speed and other rates · Grade 6
• Speed and other rates · Grade 7
• Speed and other rates · Grade 9