Rates, unit conversion and speed
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The teaching part (1 min) is free to watch. A free account opens the whole lecture: 7 practice questions, 2 real past-paper questions with the answers explained, the mistakes that lose marks, the full-marks tip, a one-card summary and a quick quiz.
What this lecture covers
- How fast is fast?
- Units to know
- Area and volume conversions
Read the transcript of the teaching part
Last time
Before we start: last time, in Upper and lower bounds, you learned these points. Here they are again on one card. Keep them in mind, because today builds on them.
How fast is fast?
A sprinter runs at ten metres a second. A car on the motorway does a hundred and twenty kilometres an hour. Which is faster? You cannot tell until the units match. Today you convert units, including area and volume, and use the speed, distance and time relationships with confidence.
Units to know
Learn these. A kilometre is a thousand metres, a metre is a hundred centimetres, and a centimetre is ten millimetres. A kilogram is a thousand grams, and a tonne is a thousand kilograms. A litre is a thousand millilitres, and a litre is also a thousand cubic centimetres. To change to a smaller unit, multiply. To a bigger unit, divide.
Area and volume conversions
For area, the conversion factor is squared. One metre is a hundred centimetres, so one square metre is a hundred times a hundred square centimetres. For volume, cube it. One cubic metre is a million cubic centimetres. So two point five square metres is twenty-five thousand square centimetres.
How often it comes up
How often Cambridge has asked each part, counted by ExamYard from every past paper in its question bank: Speed, distance and time.
The whole chapter: Ratio, Proportion and Rates.
Chapter 6: Ratio, rate and proportion
- Ratio, maps, scales and best value 5 min
- Rates, unit conversion and speed 6 min
Also for IGCSE Maths 0580
Which topics come up most in IGCSE Maths 0580 past papers, counted from every paper since 2004.