Study the graph given below of a person who started from his home and returned at the end of the day. Answer the questions that follow.



A) At what time did the person start from his home?

B) How much distance did he travel in the first hours of his journey?

C) What was he doing from 3 pm to 5 pm?

D) What was the total distance travelled by him throughout the day?

E) Calculate the distance covered by him in the first 8 hours of his journey.

F) At what time did he cover 16 km of his journey?

G) Calculate the average speed of the man from (a) A to B, (b) B to C, (c) At what time did he return home?

A) The person started from his home at 10 am, since the distance is 0 km at that time. (Note :Even though the distance at 10 pm is also 0 km, it is after the journey)

B) The first part of the graph stops at the value of 20 on the y-axis after which it first becomes constant and then starts decreasing. Hence, he travelled 20 km in the first hours of his journey.

C) The graph from 3 pm to 5 pm is parallel to the x-axis. This indicates that the person did not travel any distance in those 2 hours. So, the person was at one place from 3 pm to 5 pm.

D) He travels 20 km in the first part of the day and again travels 20 km to come back to his starting point.

∴ Total distance = 20 + 20 = 40 km.

E) The first 8 hours of the journey mean from 10 am to 6 pm. He covered 20 km up to 3 pm.

He was in the same place till 5 pm. So distance covered from 3 pm to 5 pm = 0 km.

The distance at 6 pm is 16 km and at 5 pm is 20 km.

So, distance covered from 5 pm to 6 pm = 20 – 16 = 4 km.

∴ Total distance covered in the first 8 hours = 20 + 4 = 24 km.

F) He covered 16 km of his journey at 2 pm. (Note :Even though the graph shows 16 km at 6 pm, too, the distance covered at 6 pm will be 24 km.)

G)

(a). The total distance travelled from A to B = 20 – 0 = 20 km

Now, we first need to convert 3 pm into 24 hour format.

3 pm = 12 + 3 = 15 pm

The total time taken from A to B = 15 – 10 = 5 hours

∴ Average speed from A to B = = = 4 km/hr.

(b) The total distance travelled from B to C = 0 km (since the distance is constant)

The time taken from B to C = 5 pm – 3 pm = 2 hours.

∴ Average speed from B to C = = = 0 km/hr.

(c) He returned home at 10 pm since the distance becomes 0 again at 10 pm.