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Calculus/Application of Derivatives

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Expert: - 3/12/2010


Question
At 9am ship A is 50km east of ship B. Ship A is sailing north at 40km/h and ship B is sailing south at 30km/h. How fast is the distance between them changing at noon?

Answer
It makes no difference how far A is from B when we are given how fast they are travelling.

As long as they are sailing in opposite directions, the total speed is found by taking
adding the speeds together.

If you are in the middle, both ships are sailing away from you.
This means the speeds need to be added.

If both ships were sailing the same direction, and you were in the middle,
one would be making the distance greater and the other would be making it less,
so the speeds in this case would be subtracted from each other.

Calculus

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