Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Interesting paper, require feedback

  1. Nov 20, 2003 #1
    I wrote an interesting paper, and I require feedback. Could you please check it over. Thanks in advance.

    20 joules equals 20 joules, right? Well, consider the following:

    "Ball A"
    work done = 20 joules
    force = 10 Newtons
    mass = 10 kg
    acceleration = 1 m/s²
    change in distance = 2 m
    initial velocity = 0 m/s
    final velocity = 2 m/s
    change in time = 2 s

    "Ball B"
    work done = 20 joules
    force = 10 Newtons
    mass = 0.1 kg
    acceleration = 100 m/s²
    change in distance = 2 m
    initial velocity = 0 m/s
    final velocity = 20 m/s
    change in time = 2/10 s

    Each ball experienced the same force over the same distance. And so, we can make the following statement.

    "Ball A experienced 20 joules of work
    and Ball B experienced 20 joules of work"

    So, each ball had the same amount of work done on it. Makes sense. However, if you agree that the above statement is correct, then you shouldn't be able to deny the validity of the following statement:

    "Ball A experienced 10 newtons held for 2 seconds
    while Ball B experienced 10 newtons held for 2/10 of a second"

    Thus if you agree with the first statement, then "10 newtons held for 2 seconds must equal 10 newtons held for 2/10 of a second"!

    Intuitively speaking, that's ridiculous! If you cannot see the intuitive error present here, then the following analogy may help you. Consider two classmates, Jack and Jill, both able to hold a one kilogram brick. Naturally, holding that brick on Earth is approximately equivalent to maintaining a force of 10 Newtons. Let's say that Jack held his brick for 20 seconds, and Jill held her brick for 2 seconds. Now, without pulling out any scientific jargon, who did the most work? If you try to answer that question in plain English, then I'm sure you will see the intuitive error.

    This leaves the joule system for work in a bit of a muddle, and I fully agree that I'm not exactly sure how to explain this short-coming, even though I'm sure I have the start.

    We saw from the analogy that, in plain English, Jack did more work than Jill. Thus we also see that work should be (intuitively speaking) proportional to force and a duration of time. Using that as a defintion for work, we find that "W=Ft".

    When you learn about physics, and you first encounter the term "force", you are told that it is a form of energy. Likewise, when you encounter "work", you are again told that it is a form of energy. It is true that both are forms of energy, but they are obviously not equivalent. The difference between the two is never explained. If we allow "work to equal force multiplied by time" then we have a wonderful explanation: Force and work are both forms of energy, but they are apparent in different "time frames". That is, work requires a duration of real time for an effect to be experienced, meanwhile, force requires an infinitesimal amount of time to have an effect experienced.

    We can also attack this problem from another angle, and also arrive at "W=Ft".

    Force equals mass times acceleration. Intuitively speaking, it is blindingly obvious that force should be proportional to mass and to acceleration. However, why isn't there a "coefficient"? And why not "mass squared" or "acceleration cubed"? The equation is how it is because of two things; one, intuitively, it makes sense not to add extra "factors", and two, it simply gives the "right answers".

    Now, let's examine the equation for work, that is "W=½mv²". Intuitively speaking, it is blindingly obvious that work is proportional to mass and to velocity. However, we added "factors" to the equation. Without using scientific or mathematical jargon, I say that we should be able to describe the equation for work in plain English, like we did for force. This equation is how it is because of only one thing; it "works". Meanwhile, if we remove all the extra "factors", and say that "work equals mass multiplied by velocity" ("W=mv"), then we have again arrived at the equivalent equation "W=Ft".

    I said that the equation "W=½mv²" is how it is because of one thing, it "works". But does it really? Consider dropping a brick from the height of one meter above the ground. Drop it, and the brick falls. Now, it is said that when you lift the brick up to one meter, then you have given the brick a "potential energy". But let's consider two scenarios, Jack and Jill, each lifting the brick from the ground to one meter above the earth. Jack lifts it in 20 seconds while Jill lifts it in 2 seconds. True, the outcome is the same for either participant. However, in plain english, Jack did more work; he did the same amount of "useful" work, but he did a whole lot of "useless" work by taking his time.

    Now, work defined as it is today, is wrong intuitively, but nonetheless, it is a very useful "measuring tool". That is, it calculates "useful" work, but not "useless" work. And intuitively, work should encompass both "useful" and "useless" work.

    I know that what I call work is called momentum. And so I assert that work and momentum should be equivalent and synonymous. And I propose that the real unit for work (that is, force multiplied by time) should be "P", for Prescott, Joule's middle name. Thus, one Prescott equals one newton second.

    The law of conservation of energy is wrong! There are two reasons for this:

    1) The Joule system is wrong (it only encompasses "useful" work)
    2) Attributing potential energy to objects is usually wrong

    In reality, energy is being created all around us instantaneously (it cannot be destroyed instantaneously). When energy is created instantaneously, its immediate affect on the system will be nothing (i.e. for forces, the vectors "cancel each other out"). After the immediate effect, and after a minute amount of real time, this instantaneous energy will be found to have either done "positive work" on the system or "negative work"; that is, energy will be added to the system, or destroyed. Should this instanteous energy be sustained for a longer duration of real time, then the energy might be found to have not added or removed any energy from the system (that is, it added the same amount of energy that was removed).

    "Potential energy" should only be called that so long as the potential cannot disappear without being realised. Consider a log of wood. Hold it in the air. Nothing is happening. Drop it. It falls to the Earth, and proportionally, the Earth "falls" to the log. Pick it up again, and in doing so, we say that we are giving it "potential energy". But, now, without dropping it, burn the log. The log disappears, and with it, so does the "potential energy". The "potential energy" disappeared without being realized. So, either we say that energy was destroyed, or we say that the log never truly had a "potential".

    Now, consider a battery. Between the anode and the cathode there is a potential difference. However, can we destroy this potential energy? No. The potential energy is within the chemical bonds, and the "destruction" of the chemical will always realize the potential.


    3 inventions:
    1) The Simple Newton Engine
    2) The Semi-Circular Newton Engine
    3) The Newton Motor

    All three inventions work on Newton's law that "every action has an equal and opposite reaction." The idea is to harness the "action" and elimenate the "reaction".


    |-| 1) The Simple Newton Engine
    | |
    | |

    The Simple Newton Engine is simply a cylinder with a piston ("P"). The idea is to force the piston down the shaft either by using electromagnets or the explosion of gas. (The piston may require wheels to move about the cylinder.) The cylinder itself will move forward, and the piston will move down the cylinder. The piston must be stopped before it slams into the back of the cylinder, either by friction or by a method which converts the "negative" energy into something usuable. When the piston has reached the end, it must be moved to the front of the cylinder, perhaps by a motor.


    |-| |-| 2) The Semi-Circular Newton Engine
    |P| | |
    | | | |
    \ \ / /
    \ \ / /
    \ \___/ /

    The Semi-Circular Newton Engine is like the Simple Newton Engine, except that the piston moves through a semi-circular loop. Thus, the "negative energy" changes direction by 90 degrees, and in doing so becomes usuable energy which can propel the cylinder, or chamber, further. The internal combustion engine has four parts: the intake stroke, the compression stroke, the combustion stroke, and the exhaust stroke. As the piston moves through the Semi-circular Newton Engine, the combustion stroke for one part of the loop can be the compression stage for the other side of the loop. That leaves the intake and exhaust strokes which must fit in.


    3) The Newton Motor

    Front view:

    --------- <-- wire cylinder
    | |
    /-|\ /|-\ <-- frame (holds magnets)
    | |mmmmmmmmm| |
    | --------- |

    ||__ magnets

    Side view:

    / \ <-- wire cylinder

    | OO |
    \ || /
    __||__ <-- frame

    The Newton Motor is similar to a regular motor except that there is only a small portion of the wire exposed to magnets. Thus the frame experiences a forward movement, while the wire cylinder experiences a circular motion. Of course, this circular motion can be harnessed to power a generator.


    by Raheman Velji
  2. jcsd
  3. Nov 20, 2003 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member


    You wrote a lot of crap. I'm not really going to bother responding to most of it, but I'm going to point out the fundamental issue on which the rest of your view seems to rest.

    A quantity called "impulse" is defined as force multiplied by time. In the case of your two balls, each received a very different impulse. Because they have different masses, they responded to the different impulses differently -- impulse is also defined as the change in momentum, which depends upon mass. This should be no surprise to anyone with a freshman physics textbook.

    Neither classmate did any work, because neither altered the gravitational potential energy of the brick. If, after this experiment, both Jack and Jill dropped their bricks, the same amount of energy would be released by their collisions with the floor. Obviously then, neither Jack nor Jill did any work on the brick.

    The reason you get tired when you push a wall has nothing to do with the physical definition of work. Here's why: put the brick on a table. Observe that the table manages to hold the brick without breaking a sweat. It does nothing. The brick just sits on the table. If your muscles had the consistency of wood, you could also hold the brick without breaking a sweat. However, your muscles are stretchy, and are mostly water. Your muscle has to exert a constant force just to maintain its shape, and your individual muscle fibers are continually relaxing and stretching again -- and THAT is where your energy goes when you hold a brick. Jack and Jill get tired holding the brick not because they've done work on the brick, but because they've done work on their own bodily fluids.

    Your argument is not a new one -- in fact, it's one of the very first arguments that people usually have against the physical definitions of work and energy. Frankly, no one really cares that the physical definitions seem clumsy at first, because those definitions are far more valuable to us than would be yours for doing calculations and seeing symmetries in nature. You'll see this as you get farther along in class.

    - Warren
  4. Nov 20, 2003 #3


    User Avatar

    Well, neither did any work. If they were perfect bodies, there would be no energy changes involved. The getting tiredness is due to the imperfection of the human body. This analogy is inadequate.

    I think you are confusing force with power. With consideration of power, it becomes apparent that as the object accelerates, to maintain a constant force the power supplied (Power = Fv) must increase, making up for the difference. Force is defined as the rate of change of momentum - and that is mass dependent.

    As is apparent, the value of the energy concept comes from its invariance, and its existence as a scalar quantity. W = Ft => W = momentum, which is certainly useful, but not in the same way. We cannot calculate energy conversions easily, for example.

    If you call momentum work, what do you call work?

    I don't think this is correct at all. Also, a major shortcoming of an momentum based approach appears here - there is no final velocity. Thus, it appears for both no "work" is done at all. Also, the force applied in each case is different.

    The ashes have GPE, as does the smoke. What goes up, must....

    The electromagnets will experience an reaction force. If they are secured to the shaft, the whole shaft moves back.
  5. Nov 22, 2003 #4


    User Avatar
    Science Advisor

    Get a grip and grab a clue. Physics is not about intuition. In Newton's time it was "blindingly obvious" that a constant speed required a constant force. Physics only began to make real headway when it was understood that real measurements and concepts defined as based on those measurements, were the final authority and not intuition and pre-conceived notions.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook