Suppose the two photographs, shown in Fig. 13.1 and Fig. 13.2, had been taken at an interval of 10 seconds. If a distance of 100 metres is shown by 1 cm in these photographs, calculate the speed of the blue car.

The distance covered by the blue car (as evident from the photograph) from one white strip to another, which is measured by scale is 1.4 cm.

It is given that 1 cm is equivalent to 100 m.

Therefore, 1.4 cm is equivalent to 140 m.

Distance travelled by the car = 140 m

Time interval between the two photographs = 10 s