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Thread: If Mass Times Acceleration Equals Force Then

  1. #1 If Mass Times Acceleration Equals Force Then 
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    what does Velocity times Mass equal, i.e., MV?


    MickeyC
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  3. #2  
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    Kinetic Energy = 1/2mv^2

    Close enough?


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  4. #3 Re: If Mass Times Acceleration Equals Force Then 
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    Quote Originally Posted by cassidym
    what does Velocity times Mass equal, i.e., MV?
    momentum, p
    where are we? what are we?
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  5. #4 Re: If Mass Times Acceleration Equals Force Then 
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    Quote Originally Posted by cassidym
    what does Velocity times Mass equal, i.e., MV?
    Oh and please remember that F=ma only if the mass of the thing being accelerated is constant (which is an important if you are looking at rocket propulsion for example).
    As is often the case with technical subjects we are presented with an unfortunate choice: an explanation that is accurate but incomprehensible, or comprehensible but wrong.
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  6. #5 Re: If Mass Times Acceleration Equals Force Then 
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    Quote Originally Posted by river_rat
    Quote Originally Posted by cassidym
    what does Velocity times Mass equal, i.e., MV?
    Oh and please remember that F=ma only if the mass of the thing being accelerated is constant (which is an important if you are looking at rocket propulsion for example).
    By that do you mean that the mass of a body increases as it accelerates? For example, I seem to recall the mass of an object will become infinite if it is accelerated to the speed of light. Correct?
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    No no, you are confusion different ideas here - we are talking in a purely classical sense here so no funny relativity effects.

    I mean that if you have a wagon rolling merely on a flat surface and you carefully drop a bag of potatoes on it in such a way that you hit it square on the wagon will slow down. So you need to keep track of the mass of the object else you would miss that force on the wagon.
    As is often the case with technical subjects we are presented with an unfortunate choice: an explanation that is accurate but incomprehensible, or comprehensible but wrong.
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  8. #7  
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    the thing you are refering to is the idea that mass is highly concentrated energy and energy can me turned into matter and vica versa such as in nuclear fission. if you speed up a body to the speed of light it cannot exceed this limit but if you continue to apply force this energy will instead be turned into mass. This occurs with any moving body which has a stationary mass but is only noticable or even measurable as you approach the speed of light
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    F = d(m*v)/dt = a*m + v * dm/dt

    right?
    I demand that my name may or may not be vroomfondel!
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  10. #9  
    Forum Professor river_rat's Avatar
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    Yep, that's what i was going on about.
    As is often the case with technical subjects we are presented with an unfortunate choice: an explanation that is accurate but incomprehensible, or comprehensible but wrong.
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  11. #10  
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    cassidym
    Posted: Sun Apr 01, 2007 2:19 pm Post subject: Re: If Mass Times Acceleration Equals Force Then Reply with quote

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    river_rat wrote:
    cassidym wrote:
    what does Velocity times Mass equal, i.e., MV?


    Oh and please remember that F=ma only if the mass of the thing being accelerated is constant (which is an important if you are looking at rocket propulsion for example).


    By that do you mean that the mass of a body increases as it accelerates? For example, I seem to recall the mass of an object will become infinite if it is accelerated to the speed of light. Correct?
    No. It's because with a rocket you have to count the mass of the fuel, which is getting used up as you go.
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