What type of graph represents the speed of a railcar that is decelerating at a constant rate?

• A. Linear decreasing graph
• B. Curved graph
• C. Constant horizontal line
• D. Exponential decreasing graph

Answer: (B)

The correct choice for representing the speed of a railcar that is decelerating at a constant rate is a linear decreasing graph. In this scenario, since the railcar is decelerating uniformly, its speed decreases steadily over time. When plotted on a graph with speed on the vertical axis and time on the horizontal axis, the resulting line will have a negative slope, indicating that as time progresses, the speed decreases at a constant rate.

The linear nature of the graph reflects the consistent reduction in speed: for each equal interval of time, the decrease in speed is the same. This outcome aligns with the basic principles of kinematics, where a constant acceleration (or in this case, deceleration) leads to a linear relationship between velocity and time.

Other graph types would not correctly depict this scenario. A curved graph would imply a variable rate of acceleration, which is inconsistent with the concept of constant deceleration. A constant horizontal line suggests that the speed remains unchanged over time, indicating no acceleration or deceleration occurred. An exponential decreasing graph would indicate a rapid decrease that lessens over time, which does not apply to uniform deceleration.

Thus, the linear decreasing graph accurately represents the situation of a railcar decelerating at a constant rate.