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Homework Help: How does a gearbox work?

  1. Dec 9, 2012 #1
    1. The problem statement, all variables and given/known data

    This is related to my other thread https://www.physicsforums.com/showthread.php?t=657677

    Lets suppose i have two gears where the ratio between the rotational speed of the motor and the wheel is:

    Motor/wheel 2:1 first gear
    Motor/wheel 1:1 second gear

    2. Relevant equations


    3. The attempt at a solution

    Now i guess that in the first gear following holds


    That means that the mechanical energy on the rotational axis is the same on both sides of the gearbox?

    Is that correct?
  2. jcsd
  3. Dec 9, 2012 #2


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    Science Advisor
    Homework Helper
    Gold Member

    Yes. If you ignore losses in the gearbox then a gearbox doesn't change the power. It just trades torque and angular velocity.

    You can also think of it in terms of the law of conservation of energy. A gearbox can't store or create energy so what goes in must come out (and at the same rate = power).
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