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Homework Help: Applying Newton's Laws

  1. Oct 5, 2008 #1
    A 25,000-kg rocket blasts off vertically from the earth's surface with a constant acceleration. During the motion considered in the problem, assume that g remains constant. Inside the rocket, a 15.0-N instrument hangs from a wire that can support a maximum tension of 35.0 N.

    a) Find the minimum time for this rocket to reach the sound barrier (330 m/s) without breaking the inside wire and the maximum vertical thrust of the rocket engines under these conditions.

    b) How far is the rocket above the earth's surface when it breaks the sound barrier?


    I have no idea where to start with this problem. The answers in the back of the book are:
    (a) 25.3 seconds; 5.72 x 10^5 N/s
    (b) 4170 m
     
  2. jcsd
  3. Oct 5, 2008 #2

    hage567

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    Start by drawing a free body diagram of the weight hanging inside the rocket.
     
  4. Oct 5, 2008 #3
    Okay
     
  5. Oct 5, 2008 #4

    hage567

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    So once you have that, what do you think you can do next?
     
  6. Oct 13, 2011 #5
    A 2.49e4 kg rocket blasts off vertically from the earth's surface with a constant acceleration. During the motion considered in the problem, assume that g remains constant. Inside the rocket, a 12.4 N instrument hangs from a wire that can support a maximum tension of 36.0 N.

    a) Find the minimum time for this rocket to reach the sound barrier (330 m/s) without breaking the inside wire and the maximum vertical thrust of the rocket engines under these conditions.

    b) How far is the rocket above the earth's surface when it breaks the sound barrier?

    I have no idea what to do.
     
  7. Oct 14, 2011 #6

    SteamKing

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    Go to Post #2. Follow steps there.

    (It's better not to add new problems to old posts.)
     
  8. Oct 14, 2011 #7

    Matterwave

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    Are you mocking the other guy by making a name similar to his? I find this either very coincidental, or pretty hilarious...
     
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