Recent content by jemerlia

  1. J

    Astronomical telescope: derivation - greatest magnification (detail) formula

    Homework Statement I am seeking a derivation of the formula for greatest detail or maximum resolution of an astronomical telescope, which is: Homework Equations M = fo/foe where: M: magnification fo: focal length of objective lens foe: distance of primary image from the eyepiece...
  2. J

    What is the Average Induced EMF in a Rotating Coil?

    Comments anyone? Help and advice gratefully received... :)
  3. J

    What is the Average Induced EMF in a Rotating Coil?

    I am not using 40pi * 1200: the rotational speed is 40pi which is used in the expression which requires angular velocity in rad/s. The 40pi comes from converting 1200rpm to rad/s. I then use the value 40pi for w (omega) in the expression..l.
  4. J

    What is the Average Induced EMF in a Rotating Coil?

    Homework Statement A rectangular coil of 200 turns has a length of 200 mm and width 120 mm. The coil rotates with a constant angular speed of 1200 revolutions per minute about an axis through the midpoints of its longer sides in a uniform magnetic field of 2.4 x 10-2 T. Starting from a...
  5. J

    Longitudinal waves in a clamped metal rod

    Homework Statement The speed of sound in a metal rod is 3600 m s -1. The rod is 1.20m long and clamped at one of its ends. (a) Determine the frequency of its vibration if longitudinal waves are established in the rod and it is vibrating in its first overtone mode. (d) Determine the...
  6. J

    Prism - emergent angle anomaly

    Quite so... many thanks for your help!
  7. J

    Prism - emergent angle anomaly

    Homework Statement A ray of monochromatic yellow light is incident in air on an equilateral triangular glass prism. This ray is in the same plane as the equilateral triangular cross section of the prism; the angle between the ray and the prism face is 60°, and the refractive index of the...
  8. J

    Induced charge distribution on two different radius sphere

    I guess it's possible the larger sphere could become a dipole if the smaller sphere was small enough and hence had a much higher charge density and hence electric field. Is this correct?
  9. J

    Induced charge distribution on two different radius sphere

    Homework Statement Two insulated metal spheres of equal sizes are given equal positive charges. The two spheres are brought very close to each other without touching. Draw the new charge distribution on the spheres if one sphere is much larger than the other. Homework Equations...
  10. J

    Is This a Case of Inelastic Collision?

    Homework Statement Two wooden blocks of mass 8 kg and 4 kg respectively approach each other from opposite directions on a smooth level surface at a relative speed of 16 m s^1 . After a head-on collision they separate at a relative speed of 6 m s^1 . The initial velocity of the 8 kg block...
  11. J

    A bus, a pendulum and acceleration

    Thanks - point taken - I reworked the expressions for Fy and Fx in terms of string tension: sumFy = FTcos 10 - mg cos 20 sumFx=FT sin10 - mg sin 20 m x ax = mg cos 20. tan 10 -mg sin 20 ax =g(cos20.tan10 -sin 20) N.B. ax is x acceleration with xy co-ordinates of the slope...
  12. J

    A bus, a pendulum and acceleration

    Homework Statement A bus is descending a uniform 20 degree slope. It brakes with constant deceleration. A pendulum moves 10 degrees away from the vertical to the downward side. Find the acceleration of the bus. ....| .../| ... ../.| .../10| .../...|.../ ...O...|.../ ....|/...
  13. J

    Asymmetric initial velocity calculation

    Homework Statement A rock is thrown upwards at an angle of 35.0° to the horizontal. The rock hits a signpost 15.0 m away at a point 2.00 m above the level from which it was thrown. Calculate the initial velocity of the rock. Homework Equations d = v * t d= displacement...
  14. J

    What is the speed and direction of the wind in this vector problem?

    After further thought it was clear that your explanation was only a trivial step short of the answer. However, I would be grateful if you would please check that my reasoning is correct: (a) Wind direction - the expression 8x + 16*cos30y (x,y instead of i,j) points to the co-ordinates (8...
  15. J

    What is the speed and direction of the wind in this vector problem?

    Once again - thank you. I'm still puzzled as to how solve for two unknowns in the expression for the wind direction... the Wind is directed as = 8 i + 16*cos30 j
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