All Questions

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There is no electricity at home,I need to light a 15W CFL Bulb.Can I Do it with the help of a hamster? [closed]

We know that i)avg speed of A Hamster is 30km/hr. ii)Avg mass of hamster is 1.5 kg. From the above info: Kinetic energy=1/2 X mass X velocity^2 So, K.E=1/2 x 1.5 x 30 x 30 ...
625 views

Dielectric slab counter-intuitive formula?

For the calculation of force on one of the two equal(in magnitude, opposite in sign) point charges separated by $r$ with a dielectric slab of dielectric constant $K$ and width $d$ in between, the ...
268 views

Orbital of Hydrogen molecule

does anybody here know an analytical approximation of the bonding hydrogen orbital MOLECULE? I am looking for a good approximation to this orbital, that might be in some textbooks to get an ...
31 views

Optics of a rotated spectacle lens [duplicate]

I have just discovered that if I rotate my left spectacle lens about the vertical axis by 10 degrees in one direction, the vision in that eye becomes much crisper. Note that the sphere and cylinder ...
650 views

How to prove that we are living in a 3D world?

Is there any scientific experiment that can lead us to conclude we live in 3 dimensions without the premise of the conception of limited dimensions? Thank you all who helped in the improvement of ...
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how does international space station change its orientation?

In what way does the rotating gyroscope help in changing the orientation of the international space station in space ? Is there any other way to change the the orientation of ISS ?
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Relativity - Lorentz transformation

Can someone show me how the Lorentz transformation can be derived from the metric equation: $s^2=c^2t^2-x^2$
650 views

Could an oscillator at a high enough frequency produce light instead of radio waves?

Considering that light is in the 400-800 THz range, if you had an electrical oscillator that ran at that frequency connected to an aerial of some sort, would the antenna emit visible light, in the ...
289 views

Constrained motion in a parabolic tube [closed]

A smooth parabolic tube is placed with vertex downwards in a vertical plane. A particle slides down the tube from rest under the influence of gravity. Prove that in any position, the reaction of ...
3k views

The Energy Eigenvalue of a Wavefunction

I've been reading an introduction to quantum mechanics online, and while constructing the Schrodinger equation for a free particle, the equation $i\hbar \frac{d \Psi}{dt}=\hbar\omega\Psi$ is obtained. ...
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Force acting on a simple rigid body in space

so this is the question that's been bothering me: Say you have a simple rigid body in space that is at rest or travelling with only translational motion at a constant speed. Say that the body is ...
287 views

exponential potential in physics

given the differential equation $$-\hbar^{2}D^{2}y(x)+ae^{bx}y(x)=E_{n}y(x)$$ here $D=d/dx$ derivative are there examples in physics where this potential appears ??, i know how to solve it but ...
186 views

RGEs of the MSSM - problems with Mathematica

I'm having some troubles with the trilinear soft couplings of the MSSM RGEs. I've used the ones written in Martin's supersymmetry primer and I run them using mathematica, if I do so without taking ...
761 views

Is the convective heat coefficient always dependent on heat flux and delta T?

I'm having a difficult discussion with a colleague because I'm running heat flow simulations for a small heater (5 mm^2 area), and I insist that if we're going to run more electrical power through the ...
305 views

Rayleigh scattering in three dimensions

How does the Rayleigh scattering intensity depend on the polarization angle of the incident, linearly polarized light, and the observation angle in three dimensions?
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How do fermion and scalar masses run with energy? Is the difference in their running the core of the hierarchy problem?

Do fermion and scalar running masses run in the same way? Specifically, what are the qualitative differences in the mass beta functions for, say, scalar $\lambda\phi^4$ field theory and the fermion ...
306 views

Mechanics of Materials (pressure and temperature)

A solid right cylinder of rock core is surrounded by four rods made of mild steel (all-thread rods). The rods are placed equidistantly around the core in a square formation. The tops and bottoms of ...
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Can an object be infinitely small?

I read somewhere that the earth has to be smaller than 1 cm to become a black hole, according to Schwarzschild. Since big bang came from a singularity, I am wondering, is there any minimum volume for ...
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In nuclear fusion reaction, what is the percentage of mass converted to energy?

I read somewhere that it is about one percent of the mass, but I find this too high. Also I have done some calculations, for example, the Tsar Bomba was 50 MT bomb and weighed about 27 tons. Although ...
170 views

Light entering in a 0° angle, is there any reflection?

Is there any reflection of light that enters a new medium at a 0° angle, if the electric field is such, that it is completely in the plane of the double layer?
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Equation to estimate droplet volume falling from a needle of a known orifice diameter at a given flow rate

I am doing some research to see if there is a simple equation (or an equation that can be simplified) to estimate the volume of a drop of liquid falling due to gravity based upon the approximate flow ...
743 views

After normalizing a wavefunction I don't know how to calculate probability on an interval (-0.1 + 0.1)

This is quite large homework where I 1st had to normalize the wavefunction $\psi = Axe^{-x^2/2a}$ and I got a constant $A=\sqrt{2/(a\sqrt{\pi a})}$. How do I calculate the probability now for the ...
I have a question about equivalence principle in quantum mechanics. Consider a Schroedinger equation under gravitional field $$\left[ - \frac{1}{2m_I} \nabla^2 + m_g \Phi_{\mathrm{grav}} \right]\psi ... 1answer 125 views If transported back to the 18th century could you solve the Longitude Problem without an accurate clock? Seeing an interesting BBC article today at http://www.bbc.co.uk/news/science-environment-23514521 about the Longitude Problem, I wondered if it could have been solved, in a way practical at the time ... 1answer 220 views Reflection, transmission, absorption…how to calculate them? I was wondering whether there is an equation that enables me to calculate the reflection, transmission, absorption and polarization, when the electric field everywhere is given? Consider this: You ... 1answer 187 views Does the termination point(level) influence water flow from a pipe I get water to my home from a nearby Tank A at a certain height above ground level. I have a 1" pipe through which I get this water to my home.. I leave this water into my well by connecting a 1" tube ... 0answers 52 views What highest amount of energy can we get from a laser? Can we get high energy from laser like fusion and fission reactions ? what is highest energy we can get from laser ? 2answers 288 views Sliding force less or equal? Why is the force required to slide a magnet off a steel plate A LOT less than the force required to directly pull it off? The force required to pull the magnet can be: 20lb While the force required ... 1answer 60 views What are the properties of the Electromagnetic wave E=E_0e^{-i\omega t} My question is, whether this definition E=E_0e^{-i\omega t} includes that it is a plane wave, since I am confused by the fact that we do not have any dependence on the position. So about what kind ... 2answers 173 views Is there a star catalog for download? Is there a downloadable star catalog which not only includes positions, but also spectral class, size, etc.? A CSV file would be great for the sake of easiness. 0answers 21 views Estimating the fatigue life of elastomer diaphragm [duplicate] Disclaimer: I have asked this question before, but it got put on hold because it was judged as off-topic. I happened to disagree and explained my reasons in the comments, but they have been ignored, ... 1answer 64 views Reaction of Pu-239 to gradual increase of pressure The question "Did NASA nuke Jupiter?" while debunked immediately (non-fissile isotope was used) arose many what-if questions. What would happen if a subcritical chunk of a fissile isotope, like ... 2answers 151 views Relation between \Lambda and \Omega_\Lambda in \Lambda\mathrm{CDM} In minimal \Lambda\mathrm{CDM}, there is a parameter labeled \Omega_\Lambda, and current fits place it at around \left( \Omega_\Lambda \sim 0.73\right). Meanwhile, \Lambda enters the Einstein ... 0answers 62 views relativity - equivalent frames do not have equivalent clocks and rods In problems about relativity we have a stationary frame S and a moving frame M and two observers initially at the same reference point. Then the two frames pass each other and we measure the distance ... 1answer 406 views Looking at an iPhone through a Polarizer Maybe this is more of an Electrical Engineering question, but does anyone know why iPhones looking green/red through a linear polarizer? I find it strange that the light coming out would be ... 1answer 990 views De-broglie wavelength in electron microscope The de Broglie wavelength is given by$$\lambda\equiv\frac{h}{mv}$$Now, if we have a small body, it's wavelength will be large when it is in motion. Similarly, a large body will have small ... 1answer 409 views How to sum several thrust vector on a single object (like a plane) I'm a developer. I tried (mostly for fun) to create a realistic physic engine. I try to sum all forces (here thrust) applying to an object in two composantes: an acceleration vector and the angular ... 2answers 417 views How do I read the simple, but contradictory, Lagrangian (\mathcal{L} = x + v)? I understand the lagrangian formulation of classical mechanics, to a degree. I can derive the Euler-Lagrange equations from the "least" action principle, and equivalently can determine the equations ... 1answer 551 views Mass of empty AdS_5 Five dimensional empty AdS_5 space has mass$$ E = \frac{3 \pi \ell^2}{32 G}. $$Is the above equation correct? Let's do some dimensional analysis to confirm. In natural units, in 5 dimensions ... 1answer 111 views An electron emits a photon and the core is pushed (recoiled) back! I have come across a problem which is a homework indeed, but i tried to pack this question up so that it is more theoretical. What I want to know is: If I am allowed to write energy conservation for ... 2answers 365 views Force on carabiner from free fall [closed] Suppose I weigh about 75~\text{kg} and I am attached to a (non-elastic) rope which is attached to a carabiner which can take at least 20~\text{kN}. Suppose furthermore that I reach terminal ... 0answers 193 views Can flux pinning be used for propulsion in Earth's magnetic field? I was wondering if the following steps would result in a net displacement on a spacecraft operating in Earth's magnetic field: Turn on a superconductor Use a linear actuator to shift some mass Turn ... 2answers 92 views A question about surface term of ghost fields (skip disclaimer) Hi, I have a question in Polchinski's string theory vol I p 90, after introducing the ghost fields b_{ab} and c^a, it is claimed The equations of motion then provide a ... 0answers 155 views Adiabatic quantum evolution of single photon or biphoton system The prerequisite for adiabatic quantum evolution of single photon or biphoton system is as follows. We have to prepare a single photon or biphoton quantum system which has a ground and a higher level ... 1answer 1k views Lagrangian and conservation of energy If Lagrangian of the motion is$$\mathcal{L}=\frac{1}{2}m\left(a^2\dot\phi^2+a^2\dot\theta^2\sin^2\phi\right)+mga\cos\phi, how can I show that total mechanical energy is conserved? I've read ...
A speedway turn, with radius of curvature $R$, is banked at an angle $\theta$ above the horizontal. If there is a coefficient of static friction, $\mu_{s}$ between the tires and the track, what are ...