Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook