Question

(b) at the end of a race, a runner slows down.

Explanation:

Step1: Analyze the relationship between speed and time

In a speed - time graph, if the speed is decreasing over time, the graph will have a negative slope.

Step2: Check each option

• The first graph has a negative slope, which means speed is decreasing as time increases. This is consistent with the runner slowing down.
• The second graph has a positive slope after an initial constant speed. This would mean the runner is increasing speed after some time, which is not what we want.
• The third graph shows a constant speed (horizontal line), so the runner is not slowing down.
• The fourth graph shows speed as zero after an initial time, which is not just slowing down but stopping.

Answer:

The first graph (the one with a negative slope) is the correct representation.