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  1. What is a moment/torque? i know the formulas m = fxd (Nm), I know how it works, what is does etc.

  2. But think of it fundamentally, how is it possible, that a force becomes greater when the arm of an object becomes larger?

  3. another point is with the seesaw if you make the arm on the other twice as long the for is twice as big, how is this possible?

  4. fundamentally what is happening?

  5. what is happening in the material?

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See this for a definition of different moments: https://en.wikipedia.org/wiki/Moment_(mathematics). You'll see that many different quantities can be derived from using moments, such as the center of mass and rotational inertia.

As for the second part of your question (involving lever arms), I think that what this comes down to is the amount of work done is the force applied times the distance over which it is applied, $W = F\Delta x$. This represents the amount of energy that you can put into a system. For a lever with a particular lever arm, if you apply a force pulling down on the lever over a certain distance, you will do a certain amount of work on the system. If you increase the lever arm to twice the length, you can apply the same force over twice the distance, and do twice the work. Or, to make your life easier, you can apply half of the force over twice the distance to do the same amount of work. This is why using a lever helps you perform work.

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  • $\begingroup$ I didn't think about it from a energy perspective, thx. But it still describes the result but not the reason why this works how it works. if you pull the lever down a certain distance you put energy in the system, what is the reason that you can do twice to work at the second point on the arm. where does the energy come from ? $\endgroup$
    – pwghost
    Commented Dec 8, 2015 at 14:55
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    $\begingroup$ @pwghost The energy comes from you pulling the lever over a longer distance than in the first case. Its an equal force applied but for a longer distance. Imagine carrying a box up two flights of stairs as opposed to one. In each case, you need the same force to overcome gravity, but going up two flights of stairs will take more energy because you are covering more distance. $\endgroup$
    – tmwilson26
    Commented Dec 8, 2015 at 15:00
  • $\begingroup$ thx for this answer, need to think about this. so what you are saying is the force of a doubled distance is proportional to double the work? $\endgroup$
    – pwghost
    Commented Dec 8, 2015 at 15:06
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    $\begingroup$ @pwghost Exactly, the formula "Work = Force x Distance" is something to remember. So doubling distance at a constant force leads to a doubled amount of work. $\endgroup$
    – tmwilson26
    Commented Dec 8, 2015 at 15:08
  • $\begingroup$ thx, but still why is the work double ? someone is pulling the lever down over a fixed distance. why on the other end the work is double ? that would imply energy is added to the system ? or : is it because the lever on the other end moves twice the distance up of what someone is pulling down ? $\endgroup$
    – pwghost
    Commented Dec 8, 2015 at 15:10

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