Which of the following best describes a condition of uniform speed?

A condition of uniform speed occurs when an object travels the same distance in equal intervals of time. In order for this to happen, the acceleration must be zero; this means that there is no change in velocity. When acceleration is zero, the speed remains constant, which is the defining characteristic of uniform speed.

In contrast, if the velocity is changing, this indicates acceleration, which directly contradicts the idea of uniformity in speed. Non-linear distance increases suggest that speed changes over time, reflecting either acceleration or deceleration. Similarly, an object in free fall experiences gravitational acceleration, causing its speed to increase while falling, which also does not align with the concept of uniform speed. Hence, zero acceleration is essential to maintaining a constant speed.