Model rocket physics: Why doesn't the motor go through the nose cone?
For those who have built those small model rockets, please help me understand a very very simple physics problem that i for some reason do not fully get. Why is it that the motor tube does not have a...
View ArticleIndependence of Trace-Partition function
I am trying to calculate the partition function of the system of two completely decoupled systems. Probability-wise, the decoupled nature means that the PDF is the product of the PDF of each subsystem....
View ArticleAmplitude of the maximums in single slit diffraction
Hello! I was trying to calculate the amplitude of the secondary maximums in the single slit diffraction. When I use the formula: $$ I = I_0 (\frac {sin(\Delta \phi /2)} {\Delta \phi /2})^2 $$ If I take...
View ArticleMercury as a plasma at 150 Kelvin
I was reading up on a theoretical engine employing the following, “Mercury plasma pressurized at 250k atmospheres, at a temperature of 150 degrees kelvin (-123° C), and swirled within its accelerator...
View ArticleIs Information a conserved quantity or not?
I've been wondering about statespace. Classically, we assume statespace is infinite (presumably so that we can depend on smooth, differentiable manifolds). But even in quantum, we assume a smooth space...
View ArticleContemplating Gyroscopic Forces for fighting robot weaponry
The premise is that whenever you watch Battlebots or Robot Wars, there's usually a robot on there which has a vertical drum spinner which weighs half the robots weight and spins at thousands of RPM,...
View ArticleClik here to view.
Velocity of The Plug
A problem I was thinking about when talking about natural circulation in a closed loop in another thread: What is the velocity of the buoyant plug? The loop is filled with water. There are no viscous...
View ArticleEquations for Spherical Resonators
I host freely for the public a web app for determining the diameter of a sphere to resonate a given frequency and sound hole diameter and length, and then download a stl file for 3D printing. I've...
View ArticleRadiation back reaction in classical electrodynamics
I've been doing some research on the topic of radiation reaction force/self force in classical electrodynamics and although there are some discussions on the internet I would like direct answers to...
View ArticleNegative pressure in a car to power it
My father has an idea is powering vehicle using negative pressure. I'm trying to explain to him that I don't think that can work. He is saying that imagine you're in space and you try create negative...
View ArticleEuler vs. Tait (steady precession vs... what?)
Good Morning When one studies body rotations, there are two general approaches one uses: Euler Angles vs. Tait-Bryan Angles. The significant difference is that: Tait–Bryan angles represent rotations...
View ArticleDeriving Non-linear acoustic wave models, equilibrium state assumption
The standard derivation in obtaining a single wave equation involves making use of the heat equation with a Taylor expansion of the equation of state, then differentiating this equation and the...
View ArticleAir tank PSI and cubic feet calculation help please
If I have a air tank that is 1 cubic feet with the pressure gauge at 0 and I pump in air to 5000 psi how many cubic feet of a 100 psi would be in that tank? Any help would be appreciated
View ArticlePickleball Physics -- Player reaction time vs aging
Out of curiosity, how fast are the hands of the pros? I have timed an exchange between BJ/ALW and JD/JI that occurred at the Baird PPA in September 2022. The ball made the (about) 14 foot trip 11 times...
View ArticleMagnetic bound state in classical mechanics
Seven years ago, I wanted to share and discuss my experiments results there but it was not possible since there was no published peer review paper yet and apparently not fulfilling forum requirements....
View ArticleThoughts about coupled harmonic oscillator system
Same instruction was given while finding value of 'g' by a bar pendulum. In the former case,does the spring obeys hooke's law while it forms a coupled harmonic oscillator system?Does the bar pendulum...
View ArticleClik here to view.
Limitation of using "post office box" to measure high or low resistance
Why meter bridge is chosen over post office box to measure low resistance?
View ArticleCan angular motion exist outside of a gravity field?
I can't find the answer anywhere here's my question. can a centrifuge exist outside a field of gravity. More specifically, in a theoretical void of nothing without stars in view or any point of...
View ArticleBasic Question about Gauge Transformations
Suppose we have an action ##S=S(a,b,c)## which is a functional of the fields ##a,\, b,\,## and ##c##. We denote the variation of ##S## wrt to a given field, say ##a##, i.e. ##\frac{\delta S}{\delta...
View ArticleClik here to view.
Realistic steering wheel angle when car follows points along a path
Good morning , I managed to simplify the physics of my car with only the centrifugal and traction forces. If I'm in control of it, the realism is acceptable for a city builder. On the other hand, I...
View ArticleArchimedes Principle - A Rock and Water Magic Trick
I understand how to measure specific gravity of a rock. One weighs the rock then tares a beaker of water and then suspends the rock on a string to observe the “weight” gain of displaced water. My brain...
View ArticleHow do fields retain their uniformity with interposing objects?
Why don't interposing objects interfere with the integrity of a field's energy between the source and its absorber? For example, the Sun's gravitational field spreads uniformly through space. If there...
View ArticleTransmission Line EM Wave vs EM Wave in Free Space
According to Maxwell’s Equations, the speed an EM plane wave in free space, far from its source, is determined by the electric constant, ε0, and the magnetic constant, μ0, such that c = 1/√( ε0 μ0)....
View ArticleInterpreting light as Maxwell's EM wave
Sometimes I cannot imagine light as the popular Maxwell's blue and red electric and magnetic wave https://simply.science/images/content/physics/Electromagnetism/em_waves/emv.jpg but I found the image...
View ArticleDetermination of electron temperature in an ion source
How to correctly determine the temperature of electrons in an ion source based on ECR? Is it possible to use the Saha equation? ##\frac{n_en_i}{n_a}=\frac{g_eg_i}{g_a}*3*10^{21} T^{3/2} e^{-J/T}##...
View ArticleMagnets, Outer space, and Rings
Awhile back there was a discussion about the following scenario: an astronaut sets free into space outside his window a round magnet so it just sits there a distance away ensuring the spaceship has no...
View ArticleReynolds Transport Theorem: differential forms and conserved quantities
Consider a fluid flow with density ##\rho=\rho(t,x)## and velocity vector ##v=v(t,x)##. Assume it satisfies the continuity equation $$ \partial_t \rho + \nabla \cdot (\rho v) = 0. $$ We now that, by...
View ArticleMoment of inertia and contact force
Two rotating cylinders are held in contact by a force F1. The force is applied through the center of one of the cylinders. One cylinder is the driving cylinder and the other is the driven cylinder ....
View ArticleSurface area and length (percent increase relationship)
Hi all, While calculating the surface area for an object, I was told the below statement. However, I am not sure is this correct, please can someone help me to explain this with an example? Is the...
View ArticleTrig functions and the gyroscope
Good Morning As I continue to study the gyroscope with Tait-Bryan angles or Euler angles, and work out relationships to develop steady precession, I notice that the trig functions cancel. I stumble on...
View ArticleWhy does ##u## need to be small to represent the Taylor expansion
Necessary condition for a curve to provide a weak extremum. Let ##x(t)## be the extremum curve. Let ##x=x(t,u) = x(t) + u\eta(t)## be the curve with variation in the neighbourhood of...
View ArticleHow do I calculate the drop force on a cord and eye bolt?
i have a question. I have set up an expierment and need some values. I have a round, 3d printed disk, 0.25 inches thick and 4 inches in diameter. In the center, i have a eye-bolt attached. I have...
View ArticleWhy is gravitational force directly proportional to the product of masses?
why is that the gravitational force proportional to product of masses why not sum of masses or something else .........
View ArticleHelp with Euler Lagrange equations: neighboring curves of the extremum
I tried writing this out but I think there is a bug or something as its not always displaying the latex, so sorry for the image. I have gone through various sources and it seems that the reason for u...
View ArticleClik here to view.
What is meant by "upper limit of work done on Earth"?
I think that the work is meant to be work done for instance in power stations. Or is it similar to work I do on a body when I lift it for example? But how can we then do that work on our Earth? I just...
View ArticleClik here to view.
How is it possible for two waves to be in phase when they have different...
May I know how is it possible for two waves to be in phase when they have different amplitude? I couldn't find any existing graphs that clearly shows how the two waves are in phase, would anyone be...
View ArticleEqualizing airflow through multi-hole orifices
I know the Bernoulli equation for calculating the air velocity through a pressurized hole, but I am wondering if one hole of a given area behaves the same as multiple holes with the same total area....
View ArticleClik here to view.
Vector calculus: line element dr in cylindrical coordinates
We were taught that in cylindrical coodrinates, the position vector can be expressed as And then we can write the line element by differentiating to get . We can then use this to do a line integral...
View ArticleMeasurement uncertainty due to thermal noise
I have a charged particle in a Penning trap. The particle motion is non-relativistic and the energy is high enough such that we can assume it is not in the quantum regime. For the purpose of the...
View Articlev=ds/dt, a=dv/dt: vdv=ads
In an introductory dynamics textbook, we often see this progression v = ds/dt ---> dt = ds/v a = dv/dt ---> dt = dv/a Equating the dt, we get: vdv=ads Now my question On the one hand, this works...
View ArticleVirial theorem and translational invariance
According to the virial theorem, $$\left\langle T\right\rangle =-{\frac {1}{2}}\,\sum _{k=1}^{N}{\bigl \langle }\mathbf {F} _{k}\cdot \mathbf {r} _{k}{\bigr \rangle }$$ where ##N## is the number of...
View ArticleRolling Motion direction of Velocity center of mass
Hi I have come across something confusing in rolling motion. If an object moves with a positive V_cm meaning to the right its angular velocity will be clockwise or negative. The formula is V_cm=wR but...
View ArticleMass dropped onto rotating disk
Picture a flat disk of radius r with a radial vane. The disk is rotating at angular velocity w. Assume the vane is straight, starts at the center and ends at the perimeter of the disk. A very small...
View ArticleClik here to view.
Forces on rotating disk object
Forces on rotating disk object Hi. Is it convenient to ask following question. Suppose we have solid circular object and 5 different moments like in the picture: In moment 1 we apply force (downwars...
View ArticleHow long does it take to reach harmful CO2 levels in a room?
• I exhale 1 kg of CO2 per 24 hours = 41.67g/h (average) • Co2 indoors after ventilation = outdoors = 400 ppm (world average) • Co2 indoors threshold = 1000 ppm (cognitive effect) • Room volume = 32.5...
View ArticleNeil DeGrasse Tyson on "sharing water" with historical figures
Hello, I've heard versions of these statements (below) from other scientists, but I've never seen anyone break them down. Do molecules in air really move (diffuse?) their way around the entire globe,...
View ArticleAre equations of motion invariant under gauge transformations?
We know that all actions are invariant under their gauge transformations. Are the equations of motion also invariant under the gauge transformations? If yes, can you show a mathematical proof (instead...
View ArticleHow does wind affect a turn for an aircraft?
First, I understand how wind effects aircraft tracking. I can do the calculations involving wind correction angles, effects on ground speed, headwind or tailwind calculations, etc. I teach it in a...
View Article