When an object travels at a steady rate with the same instantaneous speed for a period of time, the speed is called constant speed.

Here's why:

* Instantaneous speed is the speed of an object at a specific moment in time.

* Constant speed means the object's instantaneous speed remains the same throughout the entire period of time.

Think of a car driving on a highway with the cruise control set. The car's speed might be 60 mph, and that speed doesn't change, even as time passes. This is an example of constant speed.