1. Limited time only! Sign up for a free 30min personal 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!

Homework Help: Momentum. resulting velocity. Rocket

  1. Mar 9, 2008 #1
    [SOLVED] Momentum. resulting velocity. Rocket

    1. The problem statement, all variables and given/known data

    On earth, an astronaut and equipment weigh 1,960.0 N. While weightless in space, the astronaut fires a 100 N rocket backpack for 2.0 s. What is the resulting velocity of the astronaut and equipment?

    I have to be missing something. I tried using every formula given to me in class and I cannot get anywhere. Please help. Thanks.

    2. Relevant equations

    Ft= (mf)(vf)-(mi)(vi)
    Ft=ma+v(difference of m/t)

    3. The attempt at a solution
    I tried a few and can't get a relevant answer. I really do not know where to begin with the rocket.
    Last edited: Mar 9, 2008
  2. jcsd
  3. Mar 9, 2008 #2


    User Avatar
    Homework Helper
    Gold Member

    Don't worry about the rocket itself. You only care about what it does. It applies a constant force over a specified time? How does this affect the astronaut in terms of momentum?
  4. Mar 9, 2008 #3
    difference of momentum= (100N)(2.0s) = 200kgm/s

    200kgm/s= (1960N/ 9.8m/s^2) V


    I first found the difference of momentum which is force * time. then used the equation momentum=mass*velocity. Is this correct?
  5. Mar 10, 2008 #4


    User Avatar
    Homework Helper
    Gold Member

    Looks Good!:smile:
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook