distancespeed

Distance speed is a term used to describe the relationship between the distance traveled by an object and the speed at which it moves. In physics, distance is the scalar quantity that represents the total length of the path traveled, while speed is the rate at which that distance changes with time.

If velocity is the vector quantity that describes motion in a direction, then the instantaneous speed is the magnitude of that velocity. The instantaneous speed can be expressed as the derivative of distance with respect to time: speed = ds/dt. The average speed over a time interval is the total distance divided by the total time: v_avg = Δs / Δt.

Distance and speed are related but distinct from other motion descriptors. Distance is not the same as displacement, which is the straight-line change in position. Likewise, speed differs from velocity, since velocity includes direction while speed does not. For motion with changing speed, the instantaneous speed varies with time.

Units and measurement: in the International System, speed is measured in meters per second (m/s). Other common units include kilometers per hour (km/h) and miles per hour (mph). Speed can be measured directly with timers and distance measurements or inferred from velocity sensors, odometry, or radar.

Applications and examples: a car that travels 100 kilometers in 2 hours has an average speed of 50 km/h. A runner’s speed may vary over a race, with the instantaneous speed at any moment given by the slope of the distance–time curve. Distance and speed are foundational concepts in kinematics and are used in navigation, transportation planning, and sports analytics.