A student rides her bicycle home from physics class to get her physics book and then heads back to class. It takes her 21.0 min to make the 12.8 km trip home and 13.0 min to get back to class.
Calculate her average speed for the round-trip. Answer must be converted to km/h
I have no idea how to start this problem. I tried using the v= Delta (X)/ Delta (t) = 12.8/13-21 and I didn't get the right answer.
To calculate the average speed for the round-trip, you need to find the total distance traveled and the total time taken. Let's break it down step by step:
1. Calculate the distance traveled in each leg of the trip.
- The student takes 21.0 minutes to travel from physics class to her home, covering a distance of 12.8 km.
- The student takes 13.0 minutes to travel from her home back to physics class, covering the same distance of 12.8 km.
2. Find the total distance traveled.
- Since the distance traveled in each leg is the same, you can simply add them together: 12.8 km + 12.8 km = 25.6 km.
3. Find the total time taken.
- Add the time taken for each leg: 21.0 minutes + 13.0 minutes = 34.0 minutes.
4. Convert the total time taken to hours.
- There are 60 minutes in an hour, so divide the total time by 60: 34.0 minutes / 60 = 0.567 hours.
5. Calculate the average speed.
- Average speed is given by distance divided by time. In this case, average speed = total distance / total time.
Average speed = 25.6 km / 0.567 hours ≈ 45.14 km/h
So, the student's average speed for the round-trip is approximately 45.14 km/h.
To calculate the average speed for the round trip, you need to find the total distance traveled and the total time taken.
Given:
Distance traveled from class to home (one way) = 12.8 km
Time taken from class to home (one way) = 21.0 min
Distance traveled from home to class (one way) = 12.8 km
Time taken from home to class (one way) = 13.0 min
To find the total distance traveled, you need to double the one-way distance:
Total distance traveled = 2 * 12.8 km = 25.6 km
To find the total time taken, you need to add the time for going from class to home and the time for going from home to class:
Total time taken = 21.0 min + 13.0 min = 34.0 min
To convert the total time to hours, divide it by 60:
Total time taken = 34.0 min / 60 = 0.567 hours
Now, you can calculate the average speed using the formula:
Average speed = Total distance / Total time taken
Average speed = 25.6 km / 0.567 hours
Average speed ≈ 45.12 km/h (rounded to two decimal places)
Therefore, her average speed for the round trip is approximately 45.12 km/h.
d = 2 * 12.8 = 25.6 km.
t = (21+13)/60 = 0.567h.
Speed = d/t = 25.6km/0.567h = 45.2 km/h.