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A high pressureized cylinder is plugged by bound sphere.Will it spin if gas is expeld

  1. Jan 31, 2007 #1
    See the below diagram.

    It is a highly pressurized cylinder containg a sphere that does not allow air to escape, but will freely spin against the wall because there is zero friction between the two.

    If there is friction between the air and the sphere, will the ball spin clockwise if valve is opened.

    Attached Files:

  2. jcsd
  3. Jan 31, 2007 #2


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    Staff: Mentor

    Yes, it looks to me like it will spin.
  4. Feb 1, 2007 #3
    I think it will spin clockwise if the ball is on the left side of the open valve and counterclockwise if it is on the right side of the valve.
    If the ball plugs the cylinder perfectly so that gas cannot travel around it, then you should expect that as gas is released the ball will feel an unequal pressure and will either be pushed to the other side of the valve, at which point it will begin to feel a drag in the opposite direction, or it will plug the hole. (I think the latter is more likely.)
  5. Feb 2, 2007 #4
    The ball is bound about its axis so it can only spin about its axis. It can not roll to change in position on what would be the x-axis.
  6. Feb 2, 2007 #5
    In that case, if you consider it frictionless against the container but frictional against a gas, then yes, it would spin. Keep in mind the friction against a gas is very low, but as long as it feels a one-directional force, it will spin.
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