178 178 Constant rate of change 579 Exercise 17B A car travels from Bombay to Pune, a distance of 200 km, at a constant speed. The journey takes 150 minutes. Draw a distance-time graph and calculate the speed. 2 Two cars are driven in a straight line for 5 kilometres. They both go from point A to point B and start at the same time. (They are actually driving parallel to each other.) Each car travels with constant speed. The speed of car Y is twice that of car X, and the speed of car X is 40 km/h. Illustrate this with a distance-time graph. 3 The exchange rate for the Australian dollar in terms of the American dollar USS A 600 was A$1 = US$0.75. 500 Draw a straight-line graph that illustrates 400 this relationship. The axes should be as 300 shown. 200 100 0 100 200 300 400 500 600 700 800 AS 4 Find the speed for each of the following (assume constant speed): a distance travelled 120 km, time taken 2 hours b distance travelled 60 m, time taken 20 seconds c distance travelled 8000 m, time taken 20 minutes d distance travelled 200 km, time taken 5 hours 40 minutes e distance travelled 6542 m, time taken 5 minutes 20 seconds 5 Find the rate of flow from the following taps in litres per minute: a a tap which fills a 40-litre drum in 5 minutes b a tap which fills a 600-litre tank in 12 minutes c a tap which takes 17 minutes 20 seconds to fill a 180-litre tank 6 Water comes out of a tap at the rate of 15 litres per minute. a Copy and complete this table showing the amount which has come out at time f: Time in minutes, t 0 0.5 1.5 2 3 4 5 Amount in litres, A 0 b Draw a graph from the table. 7 A worker is paid $200 for 13 hours work. What is their rate of pay per hour? 8 A spherical balloon is blown up so that its volume is increasing by 8 cm every second. Sketch a graph to show how the volume of the balloon changes with time. 9 Two cars start together and travel with constant speed over a 1-kilometre straight track. Car I has speed 60 km/h, and car 2 travels at three-quarters of this speed. Illustrate this situation with distance-time graphs for both cars on the one set of axes