1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Please help i need this grade

  1. May 29, 2008 #1
    1. The problem statement, all variables and given/known data

    a 1.0*10^4kg spacecraft is traveling through space with a speed of 1200 m/s realtive to earth. a thruster fires for 2.0 min, exerting a continuous force of 25kN on the space craft in a direction opposite the spacecrafts motion . calculate the initial momentum and the fianl momentum kof the spacecraft.



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. May 29, 2008 #2

    G01

    User Avatar
    Homework Helper
    Gold Member

    You need to show work here in order to get help. Those are the rules. What have you tried so far? What are you thoughts on the problem?
     
  4. May 29, 2008 #3
    (-25*10^3)(2.0)=(1.0x10^4)(1200)+(1.0*10^4)(mvi)
     
  5. May 29, 2008 #4

    G01

    User Avatar
    Homework Helper
    Gold Member

    OK. Your big problem is with units. You have seconds on one side of the equation and minutes on the other side of the equation.

    Also, remember the equation is:

    Impulse =Change in Momentum.
    [tex]J=\Delta p=p_f-p_i[/tex]

    Check your signs on the RHS of your equation.
     
    Last edited: May 29, 2008
  6. May 29, 2008 #5
    ok so it would be 120s instead of 2.0min
     
  7. May 29, 2008 #6
    (-25*10^3)(120)= (1.0*10^4)(mvi)-(1.0x10^4)(1200)
     
  8. May 30, 2008 #7

    G01

    User Avatar
    Homework Helper
    Gold Member

    That looks good to me.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Please help i need this grade
  1. I need help please? (Replies: 1)

Loading...