question_answer

The  graph  given  below  is  the distance-time graph of an object. (i) Find the speed of the object during first four seconds of its journey. (ii) How long was it stationary? (iii) Does it represent a real situation? Justify your answer.

Answer:

                (i) Speed during first 4 s = slope of OP part of the h \[=\frac{75}{4}=18.75\,\text{m/s}\]                                 (ii)From 4s to 14s, distance is not changing with time, so it is stationary for 10s.             (iii) No, it is not a real situation because distance travelled cannot decrease with time. Moreover, time cannot flow backward as shown by QR part of the graph.