Question

A 100-meter sprint is a race using only the straight side of a racetrack. A 400-meter sprint is a race that makes one complete lap around a racetrack. Why are velocity and speed the same for a 100-m sprint but not a 400-m sprint?

Answer 1

Speed is a scalar quantity (meaning it can be measured using a single number that represents the amount), while velocity is composed of the scalar quantity plus the direction. As the 100-meter sprint only takes place in one direction, the speed and velocity for this is just the same. For the 400-meter sprint however, the direction of your speed changes as you turn for her curved part of the race. Therefore, a direction change is happening. 

Answer 2

Sample response on Edu is:

In the 100-m sprint, the displacement is 100 meters and the distance is 100 meters. This means speed and velocity are the same for the 100-m sprint. In the 400-m sprint, the distance is 400-m, but the runners stop at the same place they start so the displacement is zero. Zero displacement means zero velocity.