Question

Rita Jeptoo of Kenya was the first female finisher in the 110 th Boston Marathon. She ran the first \(10.0 \mathrm{km}\) in a time of $0.5689 \mathrm{h}$. Assume the race course to be along a straight line. (a) What was her average speed during the first \(10.0 \mathrm{km}\) segment of the race? (b) She completed the entire race, a distance of \(42.195 \mathrm{km},\) in a time of 2.3939 h. What was her average speed for the race?

Short answer

Answer: Rita's average speed during the first 10 km segment was approximately 17.58 km/h, and her average speed for the entire race was approximately 17.63 km/h.

Step-by-step solution

(a) Calculate the average speed during the first 10.0km segment of the race

Given that Rita ran the first 10.0km in a time of 0.5689 h, we can calculate her average speed as: Average speed = Distance / Time Average speed = 10.0 km / 0.5689 h

(a) Calculate the average speed

Now, we can compute the average speed during the first 10km segment: Average speed = 10.0 km / 0.5689 h ≈ 17.58 km/h

(b) Calculate the average speed for the whole race

Given that Rita completed the entire race (42.195 km) in a time of 2.3939 h, we can calculate her average speed again using the same formula: Average speed = Distance / Time Average speed = 42.195 km / 2.3939 h

(b) Calculate the average speed

Now, we can compute the average speed for the whole race: Average speed = 42.195 km / 2.3939 h ≈ 17.63 km/h Thus, Rita's average speed during the first 10km segment of the race was approximately 17.58 km/h, and her average speed for the entire race was approximately 17.63 km/h.