Newton's Third Law
I have a question for which I am intensely confused. Lets say a car was pushing a big truck from behind. And the car (and truck) are accelerating, then there is a breakdown because the car applies all...
View ArticleQuick question on Fourier transform
Hi all, as a physics student, I seldom use Fourier transform but from my understanding, given a periodic function you can decompose the function into sine function with different frequencies. Also, to...
View ArticleAn intuitive approach to torque's dependence on radius
Does anyone have an intuitive explanation for why torque depends on the perpendicular distance from the axis of rotation? I understand the maths and fully accept the truth of the description, but...
View ArticleDerivation of group velocity.
I was reading the derivation on Wikipedia: http://en.wikipedia.org/wiki/Group_velocity#Derivation Why is the first part before the integral sign ignored when calculating the velocity? Surely it would...
View ArticleClik here to view.
Kalman Filter - Acceleration Measurements
I am using a extended Kalman filter for the state estimation of a nonlinear system. The real system has accelerometers, so I need to include the acceleration of the system as part of my measurements...
View ArticleExpansion of a gas against a piston
So lets say a gas is doing some work against a piston and decreasing its internal energy. Does the gas also do work against gravity if it is expanding in the positive y direction? If so would it even...
View ArticleInternal energy of a gas
Hello all, So the total internal energy of a gas as far as I've been told is 3/2(NKT) but it can also be written as 3/2(PV). Why then is the internal energy only a function of temperature and not...
View ArticleCalculating pressure of supercritical water
How would I go about calculating the pressure of supercritical water at an arbitrary temperature in a closed container?
View ArticleSource terms in Maxwell's Equations and retarded positions
Hi All, Thanks again to all the great mentors and contributors to this forum. I wanted to ask a question about the Gauss's law/Ampere's law equations in Maxwell's Equations: [itex] \nabla \bullet...
View ArticleClik here to view.
How to determine direction of forces?
I am consistently getting this wrong. To me, in the picture below, it would make sense that the structure would be pulling downward, and the cable BD would be pulling upward - thus the system is in...
View ArticleQuestion about motorcycle emergency braking
Hello, I don't know if this is the right place to ask this, but here it is: Does the brake pad/rotor temp effect the stopping distance at an emergency brake scenario on a motorcycle ? Assumptions; 1)...
View Articlemotorized control valve in chilled water piping
Hi, i would like to know, why the motorized control valve have to fixed at chilled water return pipe but not in chilled water supply pipe? Is there any different if i fixed it another way round? Thank...
View ArticleTV^(gamma-1) = C
Im given this question by my Physics teacher while disscusing thermodynamics. How to Prove that Tv^gama-1 = Constant ? Please provide the mathematical derivation.
View ArticleCoulomb's experiment (coulomb's law)
Hello, I'm trying to imagine how Coulomb would've measured the force between electrically charged objects, but there are a few things I can't figure out. Is it true that Coulomb's law holds only for...
View ArticleFields in ferroelectric crystal
Hi, In the case of dielectric in electric field E0, we have E1 = E0 outside crystal and E2 = E0 - P inside, so that D1 = E1 = D2 = E2 + P. That's obvious. Now, if dielectric is ferroelectric and no...
View ArticleStatistical thermodynamics- ideal gases mixture (Reif 3.6)
A glass bulb contains air at room temperature and at a pressure of 1 atmosphere. It is placed in a chamber filled with helium gas at 1 atmosphere and at a room temperature. A few months later, the...
View ArticleRotating and kinetic energy kinematics
Hello everyone, I've run across an interesting Newtonian physics problem that I'd like some input on. The problem begins with a rotating object. Let's assume it is a slender rod rotating about one end...
View ArticleMy new video on Thermodynamics and the end of the Universe.
I have just completed another physics video. This one is on Thermodynamics, and it is at http://youtu.be/GOrWy_yNBvY It uses a physics simulation engine, along with high definition 3D graphics, to...
View ArticlePlease Help, Electromagnetic waves and their collision
Hello everyone, My Name is Dwayne McIntosh. I am not that good at Physics or Mathematics however i do have a problem. I was brainstorming the other day and i wanted to know, what if one was to use say...
View ArticleMaxwell stress tensor in different coordinate system
Hi guys, I would like to know if the answer given to this thread is correct http://www.physicsforums.com/showthread.php?t=457405 I got the same doubt, is the expression for the tensor given in...
View Article