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Homework Help: Pushy Astronaut

  1. Apr 11, 2005 #1
    Pushy Astronaut

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    a) An astronaut of mass 70 kg pushes off a satellite of mass 420 kg, exerting a force of 120 N for the 0.83 s they are in contact. What is the speed of the astronaut after they have separated?
    vastronaut = m/s

    HELP: Remember Newton's Third Law. The astronaut exerts a force on the satellite. What is the force that the satellite exerts on the astronaut?
    HELP: Apply F = ma. You can figure out the force from the Third Law. You know the mass so you can find the acceleration. Once you know that, apply kinematics to find the speed.


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    b) What is the speed of the satellite after they have separated?
    vsatellite = m/s


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    c) How far apart are they after 1 minute?
    D= m

    I request some intial help with these parts thanks,
     
  2. jcsd
  3. Apr 11, 2005 #2
    I know you know the basics of energy, thats all you need for these problems.

    edit: not energy, momentum. im stupid.
     
    Last edited: Apr 11, 2005
  4. Apr 11, 2005 #3
    Impulse 'J' = Force * Delta t, Is this right

    Impulse = Change in Momentum = mv-MV
    so,

    Given: Force = 120 N , delta t = 0.83 seconds.

    m - mass of the astronaut = 70 kg
    M - mass of the satellite = 420 kg

    To find: Speed of the astronaut v_astronaut ( in m/s)

    mv-MV = 120 * 0.83 = 99.6 Ns

    Then what,,.......
     
  5. Apr 11, 2005 #4
    [tex] Ft = mv [/tex]

    F = 120, t = 0.83. The same force is applied to both the rocket and the ship. So then:

    [itex] v = \frac{Ft}{m} [/tex] for each component.
     
  6. Apr 16, 2005 #5
    Thanks, whozum, I finally got them all.!
     
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