A bus with an acceleration of 0 but a non-zero speed is moving at a constant velocity.

Here's why:

* Acceleration is the rate of change of velocity. If the acceleration is 0, this means the velocity is not changing.

* Velocity is a vector quantity, meaning it has both magnitude (speed) and direction.

* Speed is the magnitude of the velocity.

Therefore, a bus with zero acceleration and non-zero speed is moving at a constant speed in a straight line. It's not speeding up, slowing down, or changing direction. Think of it like cruising down a highway at a steady 60 mph.