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stopandthink

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Posts posted by stopandthink

  1. Great! so now I understand how to find the definite integral of two positive points on the x axis. And also that I must add a constant to an Indefinite Integral. Although, I'll admit that I'm confused now with finding the definite integral of positive negative limits. Basically I just split it into parts, get the absolute value, and then add both parts, I think?



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    hold on so if someone asked for the definite integral of your example would you give them 0 or 16 as the answer? I see that area is not the same as definite integral. Hmmm

  2. [math] \int_{0}^{4}x^2 dx=? [/math] is this how you start it off?



    No ones asking me, I'm simply trying to learn how to integrate on my own. I just chose those points for simplicity



    Okay I think I figured it out..

    So first i take the integral of my function [math]x^2[/math] which is [math]1/3x^3[/math]

    then I plug in 4 for x and get 21.3

    then I plug in 1 for x and get 0.3

    then I subtracted 21.3 - .3 = 21

     

    sweet!

     

  3. My mass- 72kg

    speed of light- 186000 miles/sec

     

    [math] E=72(1.86*10^5)^2[/math]

    correct?

     

    So we all have a great amount of potential energy, but since i'm made of stable atoms then its almost impossible to ever use that energy? correct?

  4. I'm not a specialist in cosmology so i won't be surprised if most of this is incorrect.

     

    Everything we can see, in the universe, travels from point A to B, in waves.

    So i know when i look at the sun, I'm seeing it how it was 8 minutes ago. But when we look through a powerful telescope we can see nebula's and galaxies further away from us in space, whose waves are just arriving from a long trip through space. And just like the sun we can observe them how they once looked. But since space is expanding we must also take into consideration that the light took longer because new space was forming as it traveled. Making it cover more distance but also having more distance to cover ahead towards it's destination. I'm not sure how much new space is formed per light year, but i presume it's not much. Anyway taking all this into consideration i can now assume that what i'm looking at are photons ,from galaxies in the past, that were once way closer, but in reality they are actually further away in space.

    My question is how do cosmologist, physicist, etc.. calculate a "finite" observable universe when space is probably bigger than what we think it is? If it's measured by observation then all were doing is measuring the past.

  5. Nice video, pity it's the wrong explanation.

    Each molecule of oxygen consumed oxidising carbon is replaced by a molecule of CO2.

    With a wax candle you will get some net contraction because the oxygen that combines with hydrogen will be converted to water which condenses.

    However, as Joatmon points out, this works with paper

    Paper is mainly cellulose.

    let's have a look at the equation

    (C6H10O5)n, + 6n O2 ---> 6n CO2 + 5n H2O

     

    In this case, there's no net reduction in volume.

    CO2 isn't that soluble in warm water, so that's not the reason.

     

    At about 2:50 in that video you can see bubbles escaping from under the glass as it's put over the flame.

    That's because the air is heated and expands.

    When it cools down again it contracts and that's what causes the reduction in pressure.

     

     

    She corrected herself in the info under the video.

    "CORRECTION: The pressure inside the glass increases as the fire heats up the molecules. Oxygen is being "consumed" by the fire, that produces Carbon Dioxide (the matter itself remains, no matter is mysteriously 'vanishing' or 'created' out of nothing!). But now, the pressures are different and therefore the water outside the glass are pushed inwards — the lower pressure of the INSIDE 'sucks in' the liquid around it under the pressure stabilizes."

  6. Ok, i think i understand better now what the derivative is. By drawing out a graph [math]f(x)=x^2[/math] with x=time(in seconds), y=velocity(mph)

     

    So when [math] \frac{2seconds} {4mph}[/math], [math] \frac{3seconds} {9mph}[/math] So the difference is 5mph, but as you get closer and closer to exactly 3 seconds you find that it's instantaneous velocity(derivative) is 6mph...?

  7. I'm not expecting a different answer because i know how to find the "derivative", Of this simple function.

     

    Ok, so i think of a derivative as rise/run=slope... and i can find the slope of a secant line easily but what we want to do is get

    the secant line as close to the tangent line.

    So when we do arrive at the tangent line, we find that it's 8.... but i have no clue as to what i'm looking at on a graph with this number..

  8. I know that it's when a secant line gets closer and closer to the tangent line at the co-ordinates (4, 16) ... so when we get really close we get 8 as a "derivative"... but i still know nothing about a derivative.

  9. Yes. Here's their calculator information page:

     

    http://www.actstuden...calculator.html

    Thank you, I was hoping i could use it.

     

    As far as I know the FAFSA is need-based rather than merit-based, so it doesn't require ACT scores -- but it's been four years since I've gone through this process, so don't take my word for it.

    I still need a good score to get into a decent college tho.

     

     

     

  10. I take the ACT test on the 27th of this month.

    And I'm sure it's not as difficult as I think it is, but i could be wrong.

    I'm really stressing about it because I plan on applying for FAFSA, and of course a higher score means a better chance of getting financial help.

     

    Any advice? any at all..

  11. Yeah, though I would write it like this to avoid confusion

     

    [math] (x^2+2dx(x)+dx^2)\times(x+dx) [/math]

     

    Could you explain how to use the foil method on this?

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    I'm just going to review the binomial theorem. smile.gif

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