Recent content by ajcoelho

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    RC Circuit: How Does Current Flow?

    Homework Statement My question is very simple and perhaps it has an obvious answer. So, if we have a simple RC circuit with and EMF battery, a resistance and a capacitor, when the capacitor is charging, electrons leave the negative terminal of the battery and accumulate on one of the...
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    Does an Electromagnet Create Charge?

    Homework Statement Suppose you have a simple electromagnet. In the middle of the coil you have a magnet oscilllating. Thus, there will be an induced current in the coil. But where the electrons of this current come from? Do they come from the atoms that form the coil? Homework Equations...
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    Determination of moment of inertia

    Ty = Mg/2 = T cosϕ therefore: T = mg/2cosϕ therefore: Tx = mg sin ϕ / 2 cosϕ
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    Determination of moment of inertia

    I get it now... But i still have that cos (phi) that i have to approximate to 1 right?
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    Determination of moment of inertia

    But suppose you're viewing from end view. Then, the forces are above... So, what really makes torque isn't Tx?? Then we make Ty=Mg/2, and so on...
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    Determination of moment of inertia

    the thing is: what goes to torque equation is Tx right? Beacause Ty and Mg/2 cancell one another
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    Determination of moment of inertia

    Homework Statement I've been trying to find out what is the period os this kind of pendulum decribed here: http://www.eng.uah.edu/~wallace/mae364/doc/Labs/mominert.pdf The thing is, I've came to the same result shown in equation (11) but my reasoning it's different. I would even say that...
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    How can uncertainties in measurement affect the estimation of g?

    Exactly. I'm still not getting on how to do it...
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    How can uncertainties in measurement affect the estimation of g?

    I'm not in an advanced level. so what it was asked me to do was just an estimative of the value of the uncertainty. L +/- 0.0005 m came from the tape measure (the uncertainty is half the value of the lowest divisor scale...). I'm assuming the sphere i used in pendulum is a single point so we...
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    How can uncertainties in measurement affect the estimation of g?

    I really have to do the linear regression by eye :( So, I have an uncertainty of +/- 0.0005m for L and +/-0.01s for T (uncertainties of the tape measure and stopwatch) How can i relate these values and then estimate a GLOBAL uncertainty? I will not add all these uncertainties...
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    How can uncertainties in measurement affect the estimation of g?

    Homework Statement Hi. I don't know if this is the right place to talk about my problem. Anyway, here it is: I've made a classic experiment to find g. For that I used a gravitational pendulum and measured several periods of oscillation for differentes values of L. After that, i made a...
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    Can a 66kg Person Sit on a 24kg Table Without Tipping?

    when you say edge of the base you're referring to the supporting that has become a "pivot"?
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    Can a 66kg Person Sit on a 24kg Table Without Tipping?

    This is a very well known physics problem and i already know how to solve it. How close to the edge of a 24kg table can a 66kg person sit without tipping it over? I think everybody can see the table and what's happening in there. MY QUESTION IS: Why don't we use the normal reaction due to...
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    What is the Correct Height to Hit a Billiard Ball for Rolling Without Slipping?

    Ah, I finally get the signs <= and => ! Thanks a lot! But why should friction be smaller than that? And in this problem couldn't I use the equality to get an 'exact' answer?
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    What is the Correct Height to Hit a Billiard Ball for Rolling Without Slipping?

    So it gets: 5 F(fr) = F (7r - 5h) and now i do the replacement? 5umg = F (7r - 5h) isn't it the same?