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# Fig 8.11 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?T) (d) How far has B travelled by the time it passes C?

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

(b) since the three lines do not intersect at a single point, the three objects never meet at the same point on the road.

(c) since there are 7 unit areas of the graph between 0 and 4 on the Y axis, 1 graph unit equals 4/7 km.

Since the initial point of object C is 4 graph units away from the origin, Its initial distance from the origin is 4× $$\frac{4}{7}$$ km = $$\frac{16}{7}$$ km

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

Therefore, total distance travelled by C in this time = 8 – $$\frac{16}{7}$$ km = 5.71 km

(d) the distance that object B has covered at the point where it passes C is equal to 9 graph units.

Therefore, total distance travelled by B when it crosses C = 9×$$\frac{4}{7}$$ = 5.14 km