Larry leaves home at 2:08 and runs at a constant speed to the lamppost. He reaches the lamppost at 2:15, immediately turns, and runs to the tree. Larry arrives at the tree at 2:29. What is Larry's average velocity during his trip from home to the lamppost, if the lamppost is 308.0 m west of home, and the tree is 688.0 m east of home?
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velocity is change of position (a vector) per time.
change of position: final position-initial
= 688E+308W=380W
avgvelocity=380W/total time.
I got
avgvelocity = 380W/ total time
= 380 / 21 seconds
= 18.1 m/s
Why is my answer incorrect?
Responses
physics - bobpursley, Wednesday, October 8, 2008 at 7:09am
Rereading. The lamppost is 308m west of home.
velocity=308/time
physics - Vishnu, Wednesday, October 8, 2008 at 9:28am
308/21 = 14.66 m/s
I still get a wrong answer
It seems like there was a mistake in the calculation of the average velocity. Let's go through the steps again to determine the correct answer.
To calculate average velocity, we need to find the total displacement and divide it by the total time taken.
In this case, Larry runs from home to the lamppost, which is 308.0 m west of home. Then, he runs from the lamppost to the tree, which is 688.0 m east of home.
To find the total displacement, we need to combine the distances of both legs of the trip. Since the lamppost is west of home and the tree is east of home, we can represent the displacement as follows:
Total displacement = total distance traveled west - total distance traveled east
= 308.0 m - 688.0 m
= -380.0 m (Note: The negative sign indicates westward direction)
Next, we need to find the total time taken for the entire trip. Larry leaves home at 2:08 and reaches the lamppost at 2:15, which is a time period of 7 minutes or 420 seconds. Then, he runs from the lamppost to the tree and arrives at the tree at 2:29, which is another 14 minutes or 840 seconds. The total time taken is the sum of these two time intervals:
Total time = 420 seconds + 840 seconds
= 1260 seconds
Now, we can calculate the average velocity:
Average velocity = Total displacement / Total time
= -380.0 m / 1260 seconds
≈ -0.30 m/s (Note: The negative sign indicates westward direction)
Therefore, the correct answer for Larry's average velocity during his trip from home to the lamppost is approximately -0.30 m/s.