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General Relativity Experiment Question

  1. Oct 4, 2006 #1
    Hello, I have here a question which seems very important, I have a test in 2 days and just need some help on understanding this experiment which these questions are based off of.

    It starts off with this:

    A spacecraft is initially at rest on the surface of the Earth. It then accelerates away from Earth into a deep space where it then moves with constant velocity. There is a spring balance supporting a mass from the ceiling.

    Then it shows these three pictures:

    http://img218.imageshack.us/img218/7591/physicsexperimentqt2.png [Broken]

    And three questions ask:

    Identify and explain, in each case, the motion of the spacecraft that could give rise to the reading shown.

    1. At rest on the Earth's surface
    2. Moving away from Earth with acceleration.
    3. Moving with constant velocity in deep space.

    I just need some kind of starting point as to how to read the 3 diagrams...I don't understand how to answer these questions at all cause im not sure what it is asking me to do. Any help is greatly appreciated, thank you
    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. Oct 5, 2006 #2


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    A spring balance measures weight. Weight is a proportional to the acceleration an object experiences. think about the acceleration experienced by the mass in the rocket in each of the three situations.
  4. Oct 5, 2006 #3
    Im sorry I still dont quite understand this, if anyone can elaborate I would much appreciate this...
  5. Oct 6, 2006 #4


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    Well as per forum rules we can't give you the answers so if you tell us what you think we can tell you where you're going wrong.

    But for example think about the acceleration the mass feels when the rocket is at rest on the Earth's surface. What position/s on the spring balance would you think that corresponded to and why.
  6. Oct 6, 2006 #5
    think of elevators. if you stand in an elevators moving upward/downward and you get a balance to measure your weight, what would you get? lower/higher/equal value? or you can experiment it yourself, hold a mass on a string with your hand, when your hands accelerate downward, does the mass feel lighter? what about upward?
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