Final answer:
If the slope of a velocity-time graph gradually decreases, it represents an object undergoing negative acceleration, which means the speed of the object is reducing over time.
Step-by-step explanation:
If the slope of a velocity-time graph gradually decreases, it means that the speed of the object is reducing over time. This suggests that the object is experiencing negative acceleration. Acceleration is a measure of the rate of change of velocity. When the speed decreases with time, the acceleration is considered negative.
This can be better explained with a car as an example. Assume that a car is moving at a constant speed and suddenly the driver applies the brakes, the car will gradually decrease its speed until it comes to a halt. This decrease in velocity with time is represented as a descending slope on the velocity-time graph, showcasing that the car is undergoing negative acceleration.
Learn more about Negative Acceleration