The diagram below shows the distance-time graph for the first $100$ minutes of the journey of a fe

Question

The diagram below shows the distance-time graph for the first $100$ minutes of the journey of a ferry along a river. Find the average speed in km/h of the ferry between $t = 50$ min and $t = 70$ min. The speed increases uniformly between $t = 50$ min and $t = 70$ min. At $t = 50$ min, the speed is $0$ km/h. Hence, find the speed in km/h of the ferry at $t = 70$ min. On the grid in the answer space below, sketch the speed-time graph for the first $100$ minutes of the journey.

Accepted Answer

(a) $18$km/h (b) $36$km/h