Answer:
The speed change during the 45-minute trip is 20[mph]
Explanation:
When we see the speed at the 45 minutes this is 20 [mph] and at the 0 minutes the speed is 0 [mph].
Therefore the change is (20 - 0) = 20 [mph]
In the attached image we can see the different figures. In fig 1 we can see the bicycle's speed after 10 minutes when the speed becames constant.
In the fig. 2 we can find the graph when the biker stopped at 30 minutes and took a 15-minute break.
Figures 3 and 4, show the differences when a horizontal line is traced on a position vs time graph, and when the horizontal line is traced in a speed vs time graph.
For fig 3 we can conclude that the body is not moving therefore there is no velocity or acceleration. And for the fig 4, we can realize that the area under the horizontal line represents a displacement during the respective interval of time.