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: Recoil Speed - Zero Gravity

  1. Oct 5, 2008 #1
    1. The problem statement, all variables and given/known data

    Two astronauts are initially floating together with zero speed in a gravity-free region of space. The mass of Major Jones is 90 kg and that of Captain Smith is 70 kg. Major Jones pushes Captain Smith away so that Captain Smith attains a speed of 0.4 m/s. The recoil speed of Major Jones is:

    0.1, 0.3, 0.5, 0.7, 0.9 m/s

    2. Relevant equations

    P = Mv
    J = change in P

    3. The attempt at a solution

    I honestly have no idea.. I've searched through my textbook for any similar examples of this type of elastic collision, but I can't find anything
  2. jcsd
  3. Oct 5, 2008 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    What is the momentum of both astronauts before Jones pushes Smith?

    What is the total momentum of Smith and Jones before the push?

    What is the momentum of Smith after Jones pushes him?

    What is the total momentum of Smith and Jones after the push? (Taking into consideration that momentum is conserved.)
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook