Recent content by physicsss

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    Find Air Density: Pressure=1atm, T=273, RH=45%

    Homework Statement Given Pressure= 1 atm, Temperature=273, and Relative Humidity= 45%, find the density of air. Homework Equations 1. PV= nRT 2. density of air= M*P/(R*T), where M is the molecular weight of air. 3. M= 18*Y_H2O +M_dry_air *(1 - Y_H2O), where Y_H2O is the mole...
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    Choosing Vertices of a Polygon from Random Points on a Circle: How Many Ways?

    "Number of ways" question A circle has random points on its circumferance. How many ways can you form a quadrilateral, a triangle, and a octagon using these points? I have no idea how to get an numerical answers for this question without using n to represent the number of points on the...
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    What Is the Minimum Lifetime of a Nuclear State with 1 eV Uncertainty?

    Numerically. I got 3.291E-16, but the computer didn't accept it...
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    What Is the Minimum Lifetime of a Nuclear State with 1 eV Uncertainty?

    The energy of a certain nuclear state can be measured with an uncertainty 1 eV. What is the minimum lifetime of this state? I used (delta_E)(delta_t)=h/(4*pi) and solved for delta_t and got it wrong. Any ideas? Thanks.
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    Max Energy of UV Light Photon in Compton Collision

    What is the maximum energy a photon of UV light ( lamda= 320 nm) can transfer to an electron in a Compton collision? I used the Compton eq. and set cos= -1 and found the change in lamda to be 0.00486 nm. then using p=h/lamda where p is the momentum, i found the momentum for when lamda is 320...
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    Millikan's experiment with a twist

    bv is the upward force, and b=6*pi*n*a, where a is the radius of the oil drop and n is the coefficient of viscosity of the air. So there is also a velocity downward?
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    Millikan's experiment with a twist

    The Millikan's oil drop experiment is doen with the electric field horizontally, rather than vertically, giving the charged droplets an acceleration in the horizontal direction. The result is that the droplet falls in a straight line which makes an angle theta with the vertical. Show that...
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    Overweight Truck Crossing a Bridge

    A truck carrying chickens is too heavy for a bridge that it needs to cross. The empty truck is within the weight limits; with the chickens it is overweight. It is suggested that if one could get the chickens to fly around in the truck by banging on the truck side, it would be safe to cross the...
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    Does Special Relativity Affect Light Travel Time Between Moving Points?

    Suppose that A', B' and C' are at rest in frame S', which moves with respect to S at a speed v=056*c in the +x direction. Let B' be located exactly midway between A' and C' in S', with A' and C' 10000 km apart; all are on the x-axis. At t'=0, a light flash occurs at B' and expands outward as a...
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    Why is View Through Glass Window Not Dimmed?

    If light reflects from all surfaces, why is the view through a glass window not noticeably dimmer than the view with the window open? Can someone give me som hint? I know glass has a refractive index of 1.5...
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    Pressure Paradox: Same P1 & P2, Different Weights

    The two open tanks have the same bottom area, A, but different shapes. When the depth, h, of a liquid in the two tanks is the same in accordance with P1 = pgh + P2 the pressure on the bottom of the two tanks will be the same. However, the weight of the liquid in each of the tanks is different...
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    Calculating Water Vapor Pressure at 160 F: Understanding Fluid Mechanics

    When a fluid flows through a sharp bend, low pressure may develop in localized regions of the bend. Estimate the minimum vapor absolute pressure in psi that can develop without causing cavitation if the fluid is water at 160 F. How does one calculate the vapor pressure of water when given a...
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    Can Solar Sails Truly Escape the Solar System?

    can anyone explain to me what requirements are needed in order to escape to infinity so I can tackle part a? Thanks.
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    Angle for Impending Motion on Inclined Plane with Attached Blocks

    That's the last equation labeled translational force...
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