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I Why is it harder to run underwater but easier to lift

  1. Oct 6, 2016 #1
    Both involve water resistance, buoyancy, and density of water and air. Therefore, I would expect that the lift up of your foot would be easy but putting your foot down would be the most difficult. Lifting an object is easier bc of buoyancy force. Although, apart the object must be buoyant itself for that to work. I don't really get that bc buoyancy would still be there based on the general principles involved. I'm guessing the force wouldn't overcome the resistance possibly making it only somewhat easier.
     
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  3. Oct 6, 2016 #2

    davenn

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    hi there

    none of your comments actually addressed your question " why is it hard(er) to run under water
    And because you didn't state, I will at this point assume you are comparing it to running in air ?

    your comments never took into account the main reason for the difficulty to run under water ( other than stating what it is)
    You got side-tracked by talking about buoyancy

    do you know the reason now ?
     
    Last edited: Oct 6, 2016
  4. Oct 7, 2016 #3
    Not going to lie to you. That didn't make much sense. I thought the comparison would be obvious. I'm going to say the main reason is resistance and the water being displaced. Maybe let me ask is it turn that picking up your foot is easier underwater? Just as it is easier to pick up an object. I didn't state what was going on bc it is definitely density and resistance. I'm wondering bc I have an interest in buoyancy force right now. I think it is quite cool. It would seem to me that the foot itself is pulling up with the buoyancy force so that would be easier. However, you still have water resistance. Although, if a gold foot from an old statue needs to be lifted. I would think water resistance would come into play. However, I can still pick up my dad as a kid in the pool so that seems a bit contradictory!
     
    Last edited: Oct 7, 2016
  5. Oct 7, 2016 #4

    mathman

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    When lifting a heavy object, buoyancy is helping you. When you are trying to run, water resistance is the main problem, while buoyancy doesn't help much, since the weight involved is relatively small.
     
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