Fig below shows the distance-time graph of three objects A, B and C. Study the graph and answer the following questions:

(a) Which of the three is travelling the fastest?

(b) Are all three ever at the same point on the road?

(c) How far has C travelled when B passes A?

(d) How far has B travelled by the time it passes C?

(a) As the slope of line B is the greatest, hence, B is travelling at the fastest speed.

(b) No, as the three lines do not intersect at a single point.

(c) As there are 7 unit areas of the graph between 0 and 4 on the Y axis, 1 graph unit equals $\dfrac{4}{7}$ km.

As the initial point of object C is 4 graph units away from the origin, its initial distance from the origin is 4 x $\dfrac{4}{7}$ km = $\dfrac{16}{7}$ km

When B passes A, the distance between the origin and C is 8 km.

∴ total distance travelled by C in this time = 8 – $\dfrac{16}{7}$ km = 5.71 km

(d) Total distance travelled by B when it crosses C = 9 x $\dfrac{4}{7}$ = 5.14 km