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

Homework Help: Newton's Second Law Particle Problem

  1. Oct 14, 2007 #1
    1. The problem statement, all variables and given/known data

    While two forces act on it, a particle is to move at the constant velocity v = (3 m/s)i - (4 m/s)j. One of the forces is F1 = (2N)i + (-6N)j. What is the other force?


    2. Relevant equations

    Fnet = ma


    3. The attempt at a solution

    Well, I'm really just wanting a hint. I know that the acceleration is zero because the velocity is constant. So how do I use velocity to find the second force? Surely I'm missing something fundamental here. Once again, just a hint would be nice.
     
  2. jcsd
  3. Oct 14, 2007 #2

    PhanthomJay

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    You pretty much gave yourself a hint when you said that there is no net force. Since one of the two forces are given, what's the other one?
     
  4. Oct 14, 2007 #3

    (-2N)i + (6N)j ?
     
  5. Oct 14, 2007 #4

    PhanthomJay

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Correct! (the answer would be the same regardless of the value of the constant velocity).
     
  6. Oct 14, 2007 #5
    Oh okay! Thanks!
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook