Question

a car is moving downhill along a road at a constant speed. which graph is the speed/time graph for the car?

Explanation:

Step1: Understand constant - speed concept

A car moving at a constant speed has a speed that does not change over time.

Step2: Analyze speed - time graph characteristics

In a speed - time graph, a constant speed is represented by a horizontal line. A horizontal line means that as time (x - axis) increases, the speed (y - axis) remains the same.

Step3: Evaluate each option

• Option A: Has a horizontal line for speed, indicating constant speed.
• Option B: Has a sloping line downwards, indicating decreasing speed.
• Option C: Has a vertical line which is not a valid speed - time graph as time cannot be constant for different speeds.
• Option D: Has a sloping line upwards, indicating increasing speed.

Answer:

A.