Near the end of a marathon race, the first two runners are separated by a distance of 45.0 m. The front runner has a velocity of 3.50 m/s, and the second a velocity of 4.20 m/s. What is the velocity of the second runner relative to the first?

0.7 m/s

Explanation:

velocity of first runner = 3.5 m/s

velocity of second runner = 4.20 m/s

Both the runner are running in the same direction

velocity of second runner with respect to first runner = velocity of second runner - velocity of first runner

velocity of second runner with respect to first runner = 4.20 - 3.5 = 0.7 m/s