Question

q6 when is the runner moving at the fastest speed? a between 0-70 seconds b between 70-80 seconds c between 80-110 seconds d between 110-130 seconds

Explanation:

To determine when the runner is moving fastest, we analyze the slope of the distance - time graph. Speed is the rate of change of distance with respect to time, and on a distance - time graph, the slope of the line represents speed (slope = $\frac{\text{change in distance}}{\text{change in time}}$). A steeper slope indicates a higher speed.

• For option A (0 - 70 seconds): The line has a positive slope, but it is not as steep as the line in option C.
• For option B (70 - 80 seconds): The distance remains constant (horizontal line), so the speed is 0 (the runner is at rest).
• For option C (80 - 110 seconds): The line has a very steep negative slope. Since the magnitude of the slope (which represents speed) is larger here compared to the other intervals with non - zero speed, this means the runner is covering a large change in distance over a small change in time, so the speed is the highest.
• For option D (110 - 130 seconds): The line has a positive slope, but it is much less steep than the line in option C.

Answer:

C. Between 80 - 110 seconds