Two trains are traveling side-by-side along parallel, straight tracks at the same speed. In a time t, train A doubles its speed.
1 answer:
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Answer:
.
Explanation:
The average speed of an object is equal to total distance over total time.
- Distance traveled:
.
How much time is taken? This trip is divided into two halves, each of distance .
Time spent on the first half of the trip:
.
Similarly, time spent on the second half of the trip:
.
In total:
.
Average speed:
.
This value turned out to be slightly different from the average of the speed during the two halves of the journey. The reason is that the object traveled at each speed for a different amount of time. It spent more time at the slower speed, which gives that speed a greater weight in the average. That explains why the average speed is closer to rather than
.