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Homework Help: Need help on 2 physics problems quick!

  1. Oct 18, 2004 #1
    Hello I have 2 problem for homework. I just started physics so these problems are probably quite easy however i was not at school today and was not taught how to do them. I don't even know wher to begin so any help would be great. Anyway the problems are:

    1) Train A leaves Atlanta, heading towards Philladelphia, at a constant 92km/hr. Train B leaves Philadelphia at the same time, heading towards Atlanta, at a constant 58 km/hr. The two cities are 1250 km apart, and the tracks are strait. Find how long it takes for train a to get to Philly, How long after train A leaves do the two trains pass each other, and how far from atlanta do the two trains pass each other?

    2)An elf shoots an arrow at a retreating orc. The orc is running away at a constant 16.8 m/s, and the arrow leaves the bow at a constant 32.4 m/s. If the orc is 42m away from the elf when the arrow is fired find how far away from the elf the aroow hits the orc, and how long is the arrow in the air for.

    Thanks for your time guys.
  2. jcsd
  3. Oct 18, 2004 #2
    An example for the second one:

    Try to picture a distance-time graph... the orc is running away at a constant speed so you would see a line (going up towards the right)... you would also see the line represented by the arrow (which would be going much faster and so the line would be steeper). The point where both these lines intersect, the arrow will hit the orc. Try to model the situation using y=mx+b ... then you can solve for two equations.
  4. Oct 19, 2004 #3


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    Don't you just love the context in which these questions sometimes come?
  5. Oct 19, 2004 #4


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    A teacher in the Washington, D. C. (U.S.A) school system got into a heckofalot of trouble (and I hope will be fired!) for giving a test with questions that started:
    "You have 28 ounces of crack cocaine and... "

    "A pimp has three ho's ..."

  6. Oct 19, 2004 #5
    That's pretty cool actually... I wouldn't mind seeing something like that on a test... takes away some of the tension associated with writing tests.
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