The instantaneous speed of an object is defined as the speed of that object at a particular or specific instant of time while its speed is continuously changing.
The speed displayed on a car’s speedometer is the speed at that particular instant or moment — the instantaneous speed.
Instantaneous speed is the speed calculated in an infinitesimal amount of time.
Mathematical Expression
is the instantaneous speed or velocity.
is the infinitesimal distance and is the infinitesimal time.