Recent content by BoogieBot

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    Unusual background, need perspective & personal statement advice

    Yes, I have foggy memories of gradient, divergence, and curl in Calc III. I actually took one semester each (all that was offered) of Quantum, E&M, Classical, and Thermal during my undergrad years - the professors all gave a quick & dirty "math you need for this course" lesson during the first...
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    Unusual background, need perspective & personal statement advice

    Thanks for the reply. My overall GPA is a 2.97 (argh!). Grad-level courses in the event of rejection are a good idea - there are 2 universities in my city that have grad-level physics & astronomy programs - one of which is on my application list. I've heard of folks being admitted to grad...
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    Unusual background, need perspective & personal statement advice

    Ok, I'm applying for fall 2013 PhD programs and one masters (at an institution that funds its MS students!) in astronomy, specifically planetary science. I'm a somewhat nontraditional applicant and need some perspective on my application. I majored in English and minored in Astrophysics, but...
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    Estimating Air Mass Inside Hot Air Balloon

    Homework Statement Estimate the average temperature of the air inside a hot air balloon. Assume that the total mass of the unfilled balloon and payload is 500kg. what is the mass of the air inside the balloon? No volume or radius is given, so I estimated V = 2800 m^3 & r = 8.75 m...
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    Lagrangian mechanics: cylinder rolling down a moving mass

    Homework Statement A cylinder of mass m and radius R rolls without slipping down a wedge of mass M. The wedge slides on a frictionless horizontal surface. The angle between the wedge's hypotenuse & longest leg (which lies on the frictionless ground) is beta. The wedge's hypotenuse DOES have...
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    Emag/electrodynamics: E field in air above glass plate

    1. The plane boundary between a sheet of glass and the air lies in teh x-y plane. There is a uniform surface charge density σf= 2.0μ Coul/m2 on teh surface of the glass. The permittivity of the glass is ϵg = 3.2ϵ0. The permittivity of air is ϵ0. The electric field in the glass is E = 3000 N/Coul...
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    Moment of inertia for physical pendulum

    Ah, so then: 55*5.5^2 = 1663.75 55*11^2 = 6655 1663.75 + 6655 = 8318.75 kg-m^2
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    Moment of inertia for physical pendulum

    so: 55*5.5 = 302.5 55*11 = 605 so I for the whole pendulum is 907.5 kg-m^2, correct?
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    Moment of inertia for physical pendulum

    I have a rigid, massless strut of length 11m. A mass of 55kg is located on the free end, and another mass of 55kg is located at the midpoint. I'm having some trouble calculating the moment of inertia I for this physical pendulum. I = \int r^{2} dm (for continuous objects) I = \sum m D...
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    Pulling a sled - find friction & force exerted on puller

    1. A child pulls a sled with mass 9.0kg through the snow(note: no coefficient of friction given, but there _is_ friction between sled & snow). The sled accelerates at 1.0 m/s2. The rope exerts 27Nt on the sled in the forward direction. a) what force must the rope exert on the child...
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