Fig 8.11 shows the distance-time graph of three objects A,B and C. Study the graph and answer the following questions:

Slide19.JPG

(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?  

Answer

(a) Speed = Distance/Time

From the graph, we see that

A travels from 6 to 12 km in 2 hours

B travels from 0 to 12 km in 1.4 hours

C travels from 2 to 12 km in 1.6 hours

 

Since B travels the most distance in the smallest time,

It is travelling the fastest.

 

(b) All the three objects A,B and C never meet at a single point.

Thus, all the three were never at the same point on the road.

 

c.jpg

When B passes A, we have marked it by the blue dot.

Making a straight line from that point.

Where the straight line intersects line marked by A is the distance travelled.

Thus, distance travelled by A is 8 km

 

d.jpg

When B passes C, we have marked it by the blue dot.

At that point, Distance travelled by B is around 5 km .

  1. Class 9
  2. Chapter 8 Class 9 - Motion

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CA Maninder Singh
CA Maninder Singh is a Chartered Accountant for the past 9 years and a teacher from the past 16 years. He teaches Spoken English, Written English, Grammar and Vocabulary at Englishtan.