There isn't a single equation for constant speed, but rather a concept defined by a specific relationship between distance and time. Here's how it works:

* Constant speed means an object travels the same distance in equal intervals of time.

* Equation: This relationship is expressed by the following equation:

Speed = Distance / Time

* Speed is the rate at which an object moves, often measured in meters per second (m/s) or kilometers per hour (km/h).

* Distance is the total length traveled, measured in meters (m) or kilometers (km).

* Time is the duration of the motion, measured in seconds (s) or hours (h).

Key points:

* For an object to have constant speed, its velocity must be constant in both magnitude (speed) and direction.

* If an object changes direction, even if it maintains the same speed, its velocity changes and it's no longer considered to be moving at constant speed.

Example:

* A car travels 100 kilometers in 2 hours.

* Its constant speed is 100 km / 2 h = 50 km/h.