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    "Two protons are 1.0 × 10–14 m apart. Approximately how many times is the electrostatic force between them greater than the gravitational force between them?"


    So here is the formula for Gravitational:

     F_{g} = \dfrac {GMm}{r^2}

    and Electrostatic:

     F_{e} = \dfrac {Q_{1}Q_{2}}{4\pi\epsilon_{0}r^2  }

    So if you want to find the ratio, in this case the Electrostatic force is bigger, so you would do:

     \dfrac {F_{e}}{F_{g}}

    Right?

    So the Rs cancel out. Does this mean that the distance between them doesn't contribute to the ratio between them? I find this kinda weird, like the ratio will be the same whether the distance is 100m or 1 mm? I'm probably wrong.

    Just so people know, I did it this way and I got 2.1 x10^-74 :p: Which is wrong...lol

    Thanks
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    The ratio doesn't depend on r. You're right, odd as it may seem.
    Because it's an inverse square law, if you double the distance, the force is 4 times less for both types of force. The ratio stays the same.
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    Exactly right. If I remember correctly, the electrostatic force is 10^39 times more than the gravitational force. Just think, one small magnet can repel another upwards, even though it has the whole earth pulling down on it.

    Gravity is an exceptionally weak force!
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    So they were just messing with us when giving the distance between the protons >__>

    And anyways, how comes I get the wrong answer then?

    I do (if you rearrange it) :

     \dfrac {1}{4\pi\epsilon_{0} GMm}

    With values:

     G = 6.67 \times 10^-11

    M , m = 1.67 \times 10 ^-27

    \epsilon_{0} = 8.85 \times 10^-12

    And I get some weird answer 0_0
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    (Original post by 2710)
    So they were just messing with us when giving the distance between the protons >__>

    And anyways, how comes I get the wrong answer then?

    I do (if you rearrange it) :

     \dfrac {1}{4\pi\epsilon_{0} GMm}

    With values:

     G = 6.67 \times 10^-11

    M , m = 1.67 \times 10 ^-27

    \epsilon_{0} = 8.85 \times 10^-12

    And I get some weird answer 0_0
    charge=1.602*10^-19 C
    or easier use the charge/mass ratio given in formulae sheet
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    (Original post by rbnphlp)
    charge=1.602*10^-19 C
    or easier use the charge/mass ratio given in formulae sheet
    Oh yeh lol. I thought charge of proton was just one lol
 
 
 
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