Recent content by moonkey

  1. M

    Proving Stoke's Theorem for a Plane Curve

    Got it out Thanks again for your help LCKurtz
  2. M

    Proving Stoke's Theorem for a Plane Curve

    I think I might have been reading the question incorrectly (well hopefully). I feel like an idiot. I'll give it a go and hopefully it works out. Thanks LCKurtz
  3. M

    Proving Stoke's Theorem for a Plane Curve

    Homework Statement Let C be a simple closed plane curve in space. Let n = ai+bj+ck be a unit vector normal to the plane of C and let the direction on C match that of n. Prove that (1/2)∫[(bz-cy)dx+(cx-az)dy+(ay-bx)dz] equals the plane area enclosed by C. What does the integral reduce...
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    Prove the functions are unique in a volume, vector calculus problem

    Homework Statement In a volume V, enclosed by a surface S, the vector fields X and Y satisfy the coupled equations ∇×∇×X=X+Y ∇×∇×Y=Y−X If the values of ∇×X and ∇×Y are given on S, show that X and Y are unique in V. Homework Equations ∇.(A×B)=B.(∇×A)−A.(∇×B)...
  5. M

    Inverting Amplifier maximum output voltage

    Homework Statement I'm doing a physics lab that involves an inverting amplifier. I'm pretty crap when it comes to electronics. I've discovered that the output voltage won't go past 8Vrms. The amplifier is like the one here...
  6. M

    Probability distribution in a quantum well

    Homework Statement Consider a mixed state comprising equal components of the first two energy levels in an infinite QW of width L. These have (normalised) wavefunctions ψ1 and ψ2. The wavefunction for the mixed state will be ψ(x,t)=(1/√2)ψ1e^(iw1t)+(1/√2)ψ2e^(iω2t) a) Calculate the...
  7. M

    At what velocity should relativity be taken into account

    That makes perfectly good sense. Thanks Quinzio
  8. M

    At what velocity should relativity be taken into account

    Homework Statement I have exams coming up and I'm just looking for an idea of when relativity should be taken into account. For example I'm just going over a question involving photoelectric effect and potential fields and de Broglie and all that jazz and the final velocity of the electron...
  9. M

    At what velocity should relativity be taken into account

    Homework Statement I have exams coming up and I'm just looking for an idea of when relativity should be taken into account. For example I'm just going over a question involving photoelectric effect and potential fields and de Broglie and all that jazz and the final velocity of the electron...
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    Tension in a wire due to a standing wave

    Homework Statement Question 8 A 2m long steel wire is mounted in an insulated bath of water containing 2000 litres of water. (a) If the bath is a rectangle 2 m long and 1 m wide, what is the depth of the water The wire vibrates with a fundamental frequency of the G above middle C (392 Hz)...
  11. M

    Derivation of equation for star-planet system orbiting com

    Homework Statement (b) For a mass m1 in circular orbit with velocity v1, and a mass m2 orbiting with velocity v2 (about a common center of mass), the following holds: m1/m2 = v2/v1. Use this relation to derive an expression relating the mass and velocity of a star with the period and mass...
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    Determining the mass of the black hole at the centre of the Milky Way

    Homework Statement (2) A star orbits the centre of our Galaxy in a plane perpendicular to our line of sight. If the angular speed of this star in the sky is 40 mas (milli-arc-seconds) per year, calculate its velocity. Assume that the distance of the Galactic centre is 8 kpc. (3) If the...
  13. M

    Shining a laser pointer towards the star vega

    Thank you very much for the reply. Helped alot
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