A record of travel along a straight path is as follows:
1. Start from rest with constant acceleration of 2.77 m/s^2 for 15 s
2. Constant velocity for the next 2.05 min
3. Constant negative acceleration -9.47 m/s^2 for 4.39 s.
(a) What was the total displacement for complete trip?
(b) What were the average speeds for legs 1,2,and 3 of the trip as well as for the complete trip.
Answers in the book: (a) 5510 m (b) 20.8 m/s, 41.6 m/s, 20.8 m/s, 38.7 m/s
physics - drwls, Friday, September 7, 2007 at 1:09am
Just do it one step at a time and add the distances traveled. During part 1, the distance travelled is
(1/2) a t^2 = (1/2)(2.77)(225) = 311.6 m
The final speed attained is (2.77)(15) = 41.55 m/s. The average speed duering that interval is half of that, or 20.8 m/s
During part 2, the distance traveled is
41.55 m/s*2.05 min*60 sec/min = 5110 m/s
During part 3, the speed drops from 41.55 m/s to
41.55 - (9.47)(4.39) = 0
The average speed during this interval is 41.55/2 - 20.78 m/s and the distance travelled is 20.78*4.39 = 91.2 m/s
Total distance travelled = 312 + 5110 + 91 = 5513 m. In your book's answer, they rounded off some of the numbers differently. You can only trust the first three significant figures, hence the 5510 m answer.
How would I get the average speed for the complete trip? (38.7 m/s)
joe mama
average speed entire trip?
average speed= totaldistance/totaltime
Thanks. I thought it was more complex than that.
To calculate the average speed for the complete trip, you need to find the total distance traveled and divide it by the total time taken. In this case, the total distance is 5510 m (as given in the book answer), and the total time can be calculated by adding the times for each leg of the trip.
The time for the first leg is 15 s, the time for the second leg is 2.05 min (converted to seconds, which is 123 s), and the time for the third leg is 4.39 s. Adding these times together gives a total time of 142.39 s.
Now, divide the total distance (5510 m) by the total time (142.39 s) to find the average speed for the complete trip.
Average speed = Total distance / Total time
Average speed = 5510 m / 142.39 s
Average speed ≈ 38.7 m/s
So, the average speed for the complete trip is approximately 38.7 m/s, as given in the book answer.
To find the average speed for the complete trip, you need to divide the total distance traveled by the total time taken.
In this case, the total distance traveled is given as 5510 m (or 5513 m, depending on rounding). To find the total time taken, you need to add up the times taken for each leg of the trip.
For leg 1: The time taken for leg 1 is given as 15 s.
For leg 2: The time taken for leg 2 is given as 2.05 min. To convert this to seconds, you multiply it by 60. So the time taken for leg 2 is 2.05 * 60 = 123 s.
For leg 3: The time taken for leg 3 is given as 4.39 s.
Now, add up the times taken for each leg: 15 s + 123 s + 4.39 s = 142.39 s.
Finally, divide the total distance traveled (5510 m) by the total time taken (142.39 s) to find the average speed:
Average speed = Total distance / Total time
Average speed = 5510 m / 142.39 s
Average speed ≈ 38.7 m/s
Therefore, the average speed for the complete trip is approximately 38.7 m/s.