Question

You and your family take a trip to see your aunt who lives 100 miles away along a straight highway. The first 60 miles of the trip are driven at 55 mi/h but then you get stuck in a standstill traffic jam for 20 minutes. In order to make up time, you then proceed at 75 mi/h for the rest of the trip. What is the magnitude of your average velocity for the whole trip?

Answer 1

Answer:

51.2 mi/h

Explanation:

Total distance, d = 100 miles

First 60 miles with speed 55 mi/h

Next 40 miles with speed 75 mi/h

Time taken for first 60 miles, t1 = 60 / 55 = 1.09 h

Time taken for 40 miles, t2 = 40 / 75 = 0.533 h

Time spent to get stuck, t3 = 20 min = 0.33 h

Total time, t = t1 + t2 + t3 = 1.09 + 0.533 + 0.33 = 1.953 h

The average speed is defined as the ratio of total distance traveled to the total time taken.

Average speed = $=\frac{100}{1.953}=51.2 mi/h$

Thus, the average speed of the journey is 51.2 mi/h.