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Homework Help: Help with Newton's Third Law

  1. Sep 27, 2006 #1
    Here is the question:

    Astronauts have connected a line between their 3280 kg space tug and a 6100 kg asteroid.
    Using their ship's engine, they pull on the asteroid with a force of 490 N. Initially the tug and the asteroid are at rest, 490 m apart.
    How much time does it take for the ship and the asteroid to meet?

    -490N 490N

    So Acceleration = Force/Mass

    Acceleration for the asteroid is 490/6100 = .0803 m/s2
    Acceleration for the tug is -490/3280 = -.149 m/s2

    How do I calculate the time when given the initial speed, the distance between, and the acceleration of two objects?
  2. jcsd
  3. Sep 27, 2006 #2
    [tex] s(t) = \frac {1}{2} at^2 + v_ot +s_o[/tex] will give you position s as a function of time with a being acceleration and [tex] v_o [/tex] being initial velocity. It can be solved for t if you know all of the other components
  4. Sep 27, 2006 #3
    Thank you. I forgot about that equation. The answer is 65 seconds if anyone was interested.
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