Question

which graph illustrates constant speed?

Explanation:

Step1: Recall speed - time graph concept

Speed is constant when it does not change with time. In a speed - time graph, a horizontal line represents a constant value of speed over time.

Step2: Analyze each option

• Option A: The line is sloping downwards, which means speed is decreasing with time (negative acceleration).
• Option B: The line is sloping upwards, which means speed is increasing with time (positive acceleration).
• Option C: The line is curved upwards, which means speed is increasing at an increasing rate (non - constant acceleration).
• Option D: The line is horizontal, which means speed has a constant value over time.

Answer:

D.