Recent content by presbyope

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    Principle of virtual work invention

    Yes, the ball will slide on the surface and not rotate. The force of constraint is normal to the surface. There is no friction to overcome. The virtual work done by the forces of constraint is zero. The constraints are always defined to ensure this. In statics, since the total force is zero...
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    Principle of virtual work invention

    The example I've seen is a ball rolling down a frictionless surface. Since there is no friction, the work done by the surface is zero. That simplifies the math if you're doing Langrangian mechanics.
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    Are These Two Forms of the Doppler Shift Formula Equivalent?

    Multiply it out, group the v/c terms together and solve. You're almost there.
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    Velocity of sound in air in a closed air column

    Your calculations for the first part are good.
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    Velocity of sound in air in a closed air column

    To be extremely clear. If I measured 16.3 cm, 16.4 cm and 16.5 cm for some object I would say the average measure was 16.4 cm.
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    Thermodynamics question. Could be simpler than it looks, but I am really stuck.

    That should give you something that looks a lot like something else you're familiar with :-/
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    Thermodynamics question. Could be simpler than it looks, but I am really stuck.

    Try this: 1. the expression with T can be rewritten as two terms 2. exponentiate
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    Velocity of sound in air in a closed air column

    What quantity are you averaging? You can reduce measurement error by averaging the actual measurements you make. Is that what you are doing here? Also, what mode(s) do you expect to find at the first resonance position? Hint: the tuning fork produced a single frequency. Maybe the...
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    How can I break down the steps and solve my basic algebra homework problems?

    Hi, welcome to PF. Take a look at the worked examples here: http://tutorial.math.lamar.edu/Classes/Alg/SolveLinearEqns.aspx They are similar to yours. If you get stuck post your work here.
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    Understanding Forces Between Molecules and Temperature Changes in Substances

    But you already answered the other questions! Have some confidence.
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    Understanding Forces Between Molecules and Temperature Changes in Substances

    It's so badly worded. All chemical bonds/intermolecular forces are electrical. It's common to say that solids are held together by electrostatic forces in the sense that electrons are shared across atoms. (Think covalent, ionic, metallic.) Those forces aren't what is asked for though, because...
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    Solve Beer's Law: Find Phenolphthalein Concentration from 0.80 Absorbance Unit

    Cuvet length is 1 cm by convention. Molar absorptivity is going to vary with temperature and pH as you can see here: http://pubs.acs.org/doi/full/10.1021/ol016823q Unfortunately they don't report a value for phenolphthalein but estimating from Fig. 6, e should be about 1770/(M.cm) at 20C...
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    Find formula for how much longer each day is

    http://en.wikipedia.org/wiki/Arithmetic_progression
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