# Search results

1. ### Dispersive Component of Surface Energy

Hello, I'm doing an MSc project concerned with the treatment of plastic polymers with an μ-APPJ. I have been getting a tonne of results on different plastics using an APPJ of He carrier gas with an Oxygen admixture of 1/2, 1 & 2%. However, in my analysis I'm unsure of what the dispersive...
2. ### Complaint Why Is Noone Answering My Question?

I check back every hour and my topic has 180 views but no replies from experts. Why?
3. ### Particle Flux Derivation

Homework Statement Consider a cylindrical vessel with cross-sectional area 1m^2 Derive the particle flux (1/4n\bar{v}) Homework Equations I have the solid angle: \Omega = 2π(1-cosθ) The Attempt at a Solution I'm assuming that the solid angle represents the full area that the particles...
4. ### Variational Method - Gaussian Trial Wavefucntion

Homework Statement Use the variational method with a gaussian trial wavefunction ψ(x) = Ae^{\frac{-a^{2}x^{2}}{2}} to prove that in 1 dimension an attractive potential of the form shown, no matter how shallow, always has at least 1 bound state. *Figure is of a potential V(x) that has a minimum...
5. ### LaTeX Latex: is it possible to install something to mirror microsoft word equation editor

It takes longer to write out a question and your working, than it does to even get a reply.. And that reply either never comes or is something along the lines of 'I can't tell what you've done'. Latex is so harsh to use, is it possible to install something to mirror microsoft word equation...
6. ### Normalised Energy Eigenfunction (Probability with Dirac Notation)

Homework Statement Normalised energy eigenfunction for ground state of a harmonic oscillator in one dimension is: 〈x|n〉=α^(1/2)/π^(1/4) exp(-□(1/2) α^2 x^2) n = 0 α^2=mω/h suppose now that the oscillator is prepared in the state: 〈x|ψ〉=σ^(1/2)/π^(1/4) exp(-(1/2) σ^2 x^2)...
7. ### Hermitian Operator in Inner Product

Homework Statement \int d^{3} \vec{r} ψ_{1} \hat{A} ψ_{2} = \int d^{3} \vec{r} ψ_{2} \hat{A}* ψ_{1} Hermitian operator A, show that this condition is equivalent to requiring <v|\hat{A}u> = < \hat{A}v|u> Homework Equations I changed the definitions of ψ into their bra-ket forms...
8. ### Mechanics: Coordinate systems and vector's

Homework Statement An ant walks from the inside to the outside of a rotating turntable. Write down it's velocity vector. Use polar the cartesian coordinates. Homework Equations I have already derived the velocity vector in polar coordinates which is: \hat{v} = \dot{r}\hat{r} +...
9. ### Vector Calculus: Integral Theorems

Homework Statement Question 3 part b and c Homework Equations Divergence and Stokes Theorems. Knowledge of parametrization ect ect The Attempt at a Solution I got the B field by using curl. However any attempt to resolve the flux through the top hemisphere or even the...
10. ### Relativistic Kinematics

Homework Statement The sigma Baryon Σ0 is at rest and decays to form an Λ0 and a ɣ photon. Homework Equations Mass of Σ0 is 1193 MeV/c^2 Mass of Λ0 is 1116 MeV/C^2 The Attempt at a Solution K obviously since the Σ0 is at rest, momentum must be conserved and the Λ0 and ɣ go...
11. ### Basic Integration

How do I integrate equations such as: (x^2 + y^2)^-1/2 dx ??? I've completely forgotten and I'm in Uni at the moment. I was answering a question on find the electric field of a charged rod and I couldn't finish it because I didn't know how to integrate something like this.
12. ### Electric Potentials (4 charges on corners of a rectangle)

Homework Statement A rectangle has sides of length 5cm (right and left) and 15cm (top and bottom). Top left corner has charge (q1) = -5uC Top right corner has charge A = ? Bottom left corner has charge B = ? Bottom right corner has charge (q2) = 2uC a) What are the electric...
13. ### LaTeX Latex Feature

Hi. This is a very helpful forum, but your latex feature hinders this. It's very tedious to use, and for a particularly symbol/equation heavy question, the asker (like me) is often put off having to spend another 20mins getting the question set up to ask. And not everyone has a scanner so...
14. ### Moment of Inertia of Solid Sphere

This is not homework, just my practise question for an exam. I keep getting an answer of 3/5MR^2 when the correct one is 2/5MR^2, and that was only because I fluked it by deciding to change my intergrand a little bit. I've some sources including one from hyperphysics which suggests...
15. ### Combination of Errors

This is just my own practise question. I have a relationship of r = \frac{D}{2}sin4\theta The apparent error formula is now: \left(\frac{\Lambda r}{r}\right)^{2} = \left(\frac{\Lambda D}{D}\right)^{2} + 16 \left(\frac{\Lambda \theta}{tan 4 \theta}\right)^{2} Using a standard...
16. ### Integrate 2^x

Intergrate 2^x .... lol? How would I even go about this? This is not a homework question, but I'm practising for exams.
17. ### Use of the Barometer equation

Venus's atmosphere is made up of CO2 which has a mean molecular weight of 44 atomic mass units. Given that the lower planetary temperature is 730K, use the barometer equation to determine the scale of Venus's atmosphere (the height at which pressure drops to 1/e of the surface pressure. Take...
18. ### Velocity at Perihelion

A comet is observed to have a perihelion distance of 0.6Au and a period of 341 years. Calculate it's Aphelion distance. What is the velocity of the comet at Perihelion? ------------------------------------------------- The first thing I did was remind myself of some important...
19. ### Cephid Variables

This one has me stumped: A galactic Cephid variable has a parralax of 0.002 arcseconds. What is it's distance in parsecs? A second cephid variable with the same period is 20 magnitudes fainter. What is the distance to this second star? ------- Now I worked out that the distance to...
20. ### Differential Equations again

Differential Equations again :( y'' - y' = 0 How would I go about solving this? All I know is that the equation is not linear..
21. ### Differential Equations

The general solution of the second order DE y'' + a^2y = 0 is y = A cos ax + B sin ax WTF? O_o Someone explain why?
22. ### Star Masses and Radius

Sorry noone was answering my question, and I just wanted to get this done: Homework Statement ...Hence show that the mass of the star is M = 4\pip_{c}\left(R^{3}/3 ) Homework Equations M(r) = 4 \pip_{c}\left(r^{3}/3 - r^{4}/4R) This is the mass within a radius The Attempt at a Solution I...
23. ### Astronomy - Mass of a Star

Homework Statement ...Hence show that the mass of the star is M = 4\pip_{c}\left(R^{3}/3 ) Homework Equations M(r) = 4 \pip_{c}\left(r^{3}/3 - r^{4}/4R) This is the shell mass The Attempt at a Solution I already found the shell mass via intergration, and I know that I have to build up an...
24. ### The equivilence of Power and Kinetic Energy

This isn't homework, just be going over a few concepts. I'm trying to show that the power delivered by a force equals the rate at which the particle is changing. Now P = \vec{F} \bullet \vec{v} = m\vec{a} \bullet \vec{v} = m\vec{v} \stackrel{\delta}{\delta t}V^2 This book is now telling me...
25. ### When a Taylor Series Converges

Homework Statement For what values of x do you expect the following Taylor series to converge? sqrt(x^{2}-x-2) Homework Equations I'm not too sure The Attempt at a Solution Well quite frankly I have no idea what to do. If someone can push me in the right direction I'll get the rest done.
26. ### Lorentz Contraction

I don't understand why this happens. And it's not enough to tell me 'well it happens because Simultaneity is relative' or 'Because Time dilates between frames'. I can still say I don't understand why it happens because shouldn't 2 frames adjust their measurements so that they get the same...
27. ### Mass-Luminosity-Time relation (Astronomy)

Homework Statement The lifetime of the sun on the main sequenceof the hertzprung-russel diagram is estimated to be 10^10 years. Assuming that the luminosities of stars on the upper diagram main sequence vary as mass^4, estimate the solar mass of a star for which it's main squence lifetime is...
28. ### Equation of a Wave

Homework Statement Equation of a wave is a = a°sin(ωt - kx + φ) where φ is the phase of a wave. if 2 waves with phases φ1 and φ2 interfere, show how the intensity I =a² varies as a function of the phase difference φ1 - φ2. Use one of the trigonometric double angle forumula or otherwise...
29. ### Horrible relativistic kinematics problem

Hello my name is Unto I currently study Physics (it's my first year) at the University of Bristol in England. I first came here with a really horrible relativistic kinematics problem, but I got no answers and managed to solve it myself. However you seem like nice guys, and it's always...
30. ### Mechanics, Static friction and springs

Homework Statement A block of mass m lies on a rough surface, inclined at angle theta to the horizontal. It is attached to a spring of force constant; the other end of the spring is fixed to a point on the table below the inclined block. The co-eff of static friction is mu-s and kinetic...