Graphs 3

The distance–time graph below shows the journey of Sarah walking from home to the park and then returning home.

a) Find Sarah's speed (in km/h) as she walks from home to the park.

b) For how long did Sarah rest at the park?

c) Find Sarah's speed (in km/h) as she walked home from the park.

A car travels at a constant speed. The distance–time graph for its journey shows a straight line from (0, 0) to (3, 180).

a) Calculate the speed of the car in km/h.

The table below shows the times taken by two athletes, Anna and Ben, to complete each stage of a race.

a) Who spent less total time racing (excluding rests)?

b) Calculate Anna's average stage time (excluding rests).

A train travels at a constant speed for 45 minutes and covers a distance of 54 km.

Calculate the speed of the train in km/h.

The distance–time graphs of two runners, Helen and Marco, show Helen's graph as a straight line and Marco's as a curve starting steeper and becoming less steep.

What can you say about the speed of each runner during their run? Explain your answer.

Two cyclists, Jay and Lisa, travel towards each other from towns A and B, which are 48 km apart. Jay leaves A at 09:00 and cycles at a constant speed of 16 km/h. Lisa leaves B at 09:30 and cycles at a constant speed of 12 km/h towards A.

The distance–time graph for a motorbike shows the following points: at 0 minutes, 0 km; at 15 minutes, 18 km; at 20 minutes, 18 km; at 40 minutes, 54 km.

a) Calculate the speed of the motorbike during the first 15 minutes.

b) Explain what the graph shows between 15 and 20 minutes.

c) Calculate the average speed for the whole journey.

On a distance–time graph, a line slopes downward from left to right. What does this mean about the object's movement? Explain your answer.