Question

a runner ran the marathon (approximately 42.0 km) in 2 hours and 57 min. what is the average speed of the runner in m/s? show your work for credit.

Explanation:

Step1: Convert distance to meters

Since 1 km = 1000 m, for a distance of 42.0 km, the distance $d$ in meters is $d = 42.0\times1000=42000$ m.

Step2: Convert time to seconds

2 hours and 57 minutes. 2 hours is $2\times3600 = 7200$ s, and 57 minutes is $57\times60=3420$ s. So the total time $t$ in seconds is $t=7200 + 3420=10620$ s.

Step3: Calculate average - speed

The formula for average speed $v$ is $v=\frac{d}{t}$. Substituting $d = 42000$ m and $t = 10620$ s, we get $v=\frac{42000}{10620}\approx3.95$ m/s.

Answer:

3.95 m/s