Recent content by BenjyPhysics

  1. B

    Photon collides with stationary electron

    Cool, so {{u'}_y} = \frac{{ - \frac{c}{2}}}{{{\gamma _{\frac{c}{2}}}}} = \frac{{ - \frac{c}{2}}}{{\frac{{2\sqrt 3 }}{3}}} = - \frac{{\sqrt 3 }}{4}c and the electron in the lab frame has a velocity of \frac{{\sqrt 7 }}{4}c in a direction 49.1 degrees to the initial photon trajectory. So the...
  2. B

    Ball rolling down slope (with wedge-shaped groove)

    I'm not even sure I can imagine the ball rotating about the instantaneous axis AB, and I have no idea how to visualize the trajectory of either of the contact points of the ball :( Obviously it will be a circle but I'm not sure how to figure out the radius of said circle
  3. B

    Photon collides with stationary electron

    An interesting response no doubt but I was referring to a particle of mass 'm' and speed 'u', this was the first part of the question - before a photon got involved!
  4. B

    Photon collides with stationary electron

    Hey, this question did not come with a mark scheme and I want to make sure that I am going about it in a correct manner, please could someone check what I've done (and answer a couple of questions I have raised)? Thank you in advance! :D Homework Statement Give expressions for the total...
  5. B

    Ball rolling down slope (with wedge-shaped groove)

    I'm not sure how to 'check how far it proceeds in one revolution' Could you please tell me what the angular velocity in the second case should be - so that I can understand exactly how you worked it out?
  6. B

    Ball rolling down slope (with wedge-shaped groove)

    I found omega like so v = a\omega \Rightarrow \omega = \frac{v}{a} \Rightarrow \frac{{d\omega }}{{dt}} = \frac{1}{a}\frac{{dv}}{{dt}} That^ is actually the result I used in the first derivation - but I'm not sure if it applies in the second scenario because the ball is rotating about a...
  7. B

    Ball rolling down slope (with wedge-shaped groove)

    1. Homework Statement [/b] The question is B7 here: http://www-teach.phy.cam.ac.uk/dms/dms_getFile.php?node=7787 I managed to derive the acceleration required in the first part, but the second part is giving me trouble. Homework EquationsThe Attempt at a Solution I have calculated the moment...
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