Question

3 Sarah left home at 10:00 and cycled north in

a straight line. The diagram shows a
displacement-time graph for her journey.
a Work out Sarah's velocity between 10:00 and 11:00.
On her return journey, Sarah continued past her
home for 3 km before returning.
b Estimate the time that Sarah passed her home.
c Work out Sarah's velocity for each of the last two
stages of her journey.
d Calculate Sarah’s average speed for her entire journey.​

Answer 1

a) From 10 to 11, Sarah rode 12 km in one hour. That means her velocity was 12 km/hr.

b) Sarah passed by her home at 12:45.

c) From 12 to 13, Sarah rode 15 km. Thus, her velocity was 15 km/hr. From 13 to 14 she rode 3 km. Thus, her velocity was 3 km/hr.

d) Her average velocity was 12+0+15+3/4, or 30/4 which is 7.5 km/hr.