Question

greg is in a bike race. at mile marker four (out of ten), his speed was measured at 13.5 mph. which best describes the measured number? it is the average speed of the bike rider. it is the instantaneous speed of the bike rider. it is the instantaneous velocity of the bike rider. it is the average velocity of the bike rider.

Explanation:

1. Average speed/velocity: These require total distance/time (average speed) or total displacement/time (average velocity) over a period, not a single point (mile marker four). So the first and fourth options are out.
2. Instantaneous velocity vs speed: Instantaneous velocity has direction, but the problem only gives speed (13.5 mph, no direction). Instantaneous speed is speed at a specific instant (here, at mile marker four). So the third option (involving velocity, which needs direction) is incorrect, and the second option (instantaneous speed at that marker) fits.

Answer:

B. It is the instantaneous speed of the bike rider.