Enthalpy under uniaxial compression of solid
Hello, I have found several references (I can send you the links if you want) that point to the fact that the enthalpy under uniaxial compression along z of a solid is simply given by: H=U+PzV This...
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Deriving the expression for wind velocity around low pressure area
Hi Can somebody tell me the steps and assumptions made in deriving the equation to calculate the wind velocity around a low pressure area ? (see the attachment fro Kleppner & Kolenkow). I tried to...
View ArticleOpen loop rankine cycle with no condenser
Hello, I'm working on a small scale parabolic trough concentrator project to generate electricity. This electricity is used for pumping water for irrigation,and I want to use an open loop Rankine cycle...
View ArticleHow do rockets attain high speeds?
The equation relating velocity of a rocket to it's mass is given by v1-v2 = uln(m1/m2), where v1, m1 and v2,m2 are masses and velocities at some times t1 and t2. Assuming a fuel mass to rocket mass...
View ArticleLight As a Wave
I've been comparing light as particles and waves in outer space when it occurred to me, if you throw two rocks of equal weight in to a pool side by side the waves created will cancel out. Do stars In...
View ArticleLinear and Angular momentum of a rolling object
Hi all: I have been wondering: picture a cylinder sitting above a sheet of sand paper, assume static friction between the sheet of paper and the cylinder. if i start pulling the sheet of paper at...
View ArticleHow to calculate the charge density in an electric field
I've been studying electric fields in class for some time and one thing is seemingly contradictory and really confuses me. The charge density ρ is related to the electric field E and the permiativity ε...
View ArticleA question about the fundamentality of magnetism
I'm sorry if I may be asking an unanswerable question here, but i've looked all through the forums and the internet to find a satisfying answer to why moving electric charges create a magnetic field....
View ArticleReynolds number and its relation to laminar and turbulent flow
So I understand that Reynolds number is the ratio of intertial forces to viscous forces but how exactly does this relate to flow? Why is it that when viscous forces dominate one gets a laminar flow?...
View ArticleTrajectory from differentiating action with respect to energy?
Hi... I was looking at the problem of a particle in a Coulomb field in three dimensions. Time-translation invariance and spherical symmetry ensures that the energy and angular momentum are conserved,...
View ArticleWeight and buoyancy in air
I was having a discussion with a friend and we could not come to an agreement on the following: If you were to weigh yourself on a very sensitive set of scales, would you register the amount of air...
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Moment of inertia of combined cylinders
Hi, I've attached a word document with my problem since I've used the Mathtype program (sorry, I didn't quite know how to use the tools on this forum), hope you don't mind :) Attached Files Moment of...
View ArticleHow does a bent wire keep spinning in a magnetic field?
For the basic principle of motors and electromagnetic induction, when a wire loop with a current running through it is put in a magnetic field, wouldnt it only spin until it reached a certain point...
View ArticleElectric Field and Magnetic Conversion
In the solutions of a particular problem, it was stated that: <P> = 1/2 |S| = 1/(2μ0) * E^2 / c Where <P> is the average power, S is the Poynting vector. From the above equation does that...
View ArticlePrinciple of Least Action via Finite-Difference Method
I have to be honest, the principle of least action seems to me more of a religious claim one takes on complete faith, though of course I'm hoping this is just because I don't understand it. I tried to...
View ArticleConfused on phase diagrams for binary systems (thermodynamics)
I'm confused regarding the phase diagrams of binary systems. Let's suppose we mix 2 liquids, A and B at a given pressure P that won't change during the whole experiment. I raise the temperature until I...
View ArticleConstrained Lagrangian equetion (barbell)
Hi! I tried to compute an ideal barbell-shaped object's dynamics, but my results were wrong. My Langrangian is: ## L = \frac{m}{2} ( \dot{x_1}^2 + \dot{x_2}^2 + \dot{y_1}^2 + \dot{y_2}^2 ) - U( x_1 ,...
View ArticleTemperature changes and degrees of freedom and intermolecular forces
Hi I have a couple of questions relating to these topic hope you guys can help :) Comparing ethanol and water, ethanol has weaker intermolecular forces than water. However, it has a greater specific...
View ArticleFinding change in entropy
In 250gr water at 23 oC(degrees celsius) we throw in 27gr ice at 0 oC. Find the change in entropy. (sorry if that was a bad translation but English is not my native language) The answer is 0.78...
View ArticleWhat limits axial resolution
Hi all, I was wondering what factors determine axial resolution in spherical lenses. I know that axial resolution in conventional light microscopy at least is about half as good lateral resolution....
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