Which phrase best describes wave speed?
2 answers:
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Answer:
Same direction: t=234s; d=6.175Km
Opposite direction: t=27.53s; d=0.73Km
Explanation:
If the automobile and the train are traveling in the same direction, then the automobile speed relative to the train will be (<em>the train must see the car advancing at a lower speed</em>), where
is the speed of the automobile and
the speed of the train.
So we have .
So the train (<em>anyone in fact</em>) will watch the automobile trying to cover the lenght of the train L at that relative speed. The time required to do this will be:
And in that time the car would have traveled (<em>relative to the ground</em>):
If they are traveling in opposite directions, <u>we have to do all the same</u> but using (<em>the train must see the car advancing at a faster speed</em>), so repeating the process:
The average velocity of Sandy is given by the total distance covered S divided by the total time taken t:
The total distance covered is
while the total time taken is 2 hours + half an hour (for the rest) + 1 hour and half, so
Therefore, the average velocity is
The total distance covered is
while the total time taken is 2 hours + half an hour (for the rest) + 1 hour and half, so
Therefore, the average velocity is