1. Compound Measures OCR Stage 6

2. Speed - Distance - Time Part 1

3. What is speed? • How far you travel in a certain time • Speed = Distance ÷ Time • We call the result “the average speed”

4. d s t x SDT Triangle You have seen this in Science?

5. d s t x We can use this to find any one thing IF we know the other two! By covering up what you want = d t = s x t Time? Speed? = d ÷ s Distance?

6. d s t x A train travels 120 miles in 2 hoursWhat is its average speed? s = 120 ÷ 2 = d t Speed mph s = 60 MUST give UNITS MILES per HOUR

7. d s t x A runner’s average speed is 8m/s, how far does he run in 25 seconds ? d = 8 x 25 =s x t Distance d = 200 metres MUST give UNITS Because speed was in METRES per second

8. d s t x A lorry leaves Stoke, travels 150km to Leeds at an average speed of 60km/h. How long did the journey take? t = 150 ÷ 60 = d s Time hours t = 2.5 MUST give UNITS Because speed was in km per HOUR

9. d s t x Car travels 40km in 20 minutes. What is its average speed in kph? s = 40 ÷ 1/3 = d t Speed s = 120kph

10. Density – Mass - Volume Part 2

11. What is Density? • Weight of a given amount of a material • Density = Mass ÷ Volume

12. m d v x DMV Triangle You have seen this in Science?

13. m d v x We can use this to find any one thing IF we know the other two! By covering up what you want = d x v = m d = m v Density? Mass? Volume?

14. m d v x A steel girder weighs 2500 kg and has a volume of 100m3What is its density? d = 2500 ÷ 100 = m v Density = 25 Kg/m3 MUST give UNITS Kilograms per Cubic Metre

15. Population Density Part 3

16. p d a x A town in S France has a population of 120,000 living in an area of 15km2What is the population density? d = 120 000 ÷ 15 Population density = p a people / km2 d = 8000 MUST give UNITS People per Square Kilometre