Linear Kinematics

How far a body has traveled is impressive but how fast a body travels can be more impressive and informative.  Speed and velocity are measures of how quickly we cover a distance or displacement, respectively.  The metric units for these measures are meters/second (m/s) or kilometers/second (km/s).

Speed: Speed is a scalar quantity and is the rate change in distance.

Quantitative definitions:

(1) Average Speed (s) = Δ distance/Δ time (remember Δ = change).

                        or

(2) Average Speed (s) of running = stride length (SL) x stride rate (SR)

Practice problem 1: What was a marathon runner's average speed in finishing the 42.2 km race in 2 hours 10 minutes?  
Solution:

Practice problem 2: View the animation below and quantify speed of running using equation 2 (given:  total distance = 15m; total time = 3s). Solution