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

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

6. A train travels 120 miles in 2 hours What is its average speed?
mph s d t x
MUST give UNITS
MILES per HOUR

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

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

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

10. Density – Mass - Volume
Part 2

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

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

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

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

15. Population Density
Part 3

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