Compound Measures OCR Stage 6

Compound Measures OCR Stage 6

Speed - Distance - Time Part 1

What is speed? How far you travel in a certain time Speed Distance Time We call the result “the average speed” d s t

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

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

A train travels 120 miles in 2 hours What is its average speed? s 120 2 s 60 mph MUST give UNITS MILES per HOUR Speed d t d s x t

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 MUST give UNITS Because speed was in METRES per second d s x t

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

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

Density – Mass - Volume Part 2

What is Density? Weight of a given amount of a material Density Mass Volume m d v

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

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

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

Population Density Part 3

A town in S France has a population of 120,000 living in an area of 15km2 What is the population density? d 120 000 15 Population density 2 p people / km d 8000 a MUST give UNITS People per Square Kilometre p d x a