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Just a thought experiment on fluid mechanics.

  1. Oct 21, 2013 #1
    I am thinking that....
    if a tank of water which contains a small wooden block is kept in an elevator which is accelerating upwards from rest, will the block get more dipped or remains constant position with respect to water??
    Last edited: Oct 21, 2013
  2. jcsd
  3. Oct 21, 2013 #2


    Staff: Mentor

    You are describing a thought experiment that Einstein considered while formulating GR. He was trying to resolve the apparent difference between gravitational mass and inertial mass. In the end GR postulated that they are one and the same.

    In your case, you could simply ask what how would the tank of water and block react in a heavier gravitational environment.
  4. Oct 21, 2013 #3
    So what do you think about it?:smile:
  5. Oct 21, 2013 #4
    I am grade 12 and just thinking it while reading my fluid mechanics lesson. When the lift is not accelerating the weight of the block must be equal to the buoyancy force as the block is in equilibrium. When the lift stats accelerating the mass of the block becomes m(g+a),where a is acceleration of lift. Now according to the Archimedes principle weight of the block must be equal to the weight of the water displaced by the block.So the weight of the water will be its mass*(g+a). Is my logic and maths correct??
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