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  1. X

    Tension Force question

    Any help would be very appreciated :) Edit:(had a thought) Would the tension that the cable car's cable would feel be half that of the total force being applied to the cable car since it is being essentially between two cables?
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    Tension Force question

    Question: The cable cars in San Francisco are pulled along their tracks by an underground steel cable that moves along at 9.5mph. The cable is driven by large motors at a central power station and extends, via an intricate pulley arrangement, for several miles beneath the city streets. The...
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    Relativistic density

    You say old-fashioned. Do they now use it in the way relating it to the Energy of the particle. Such as in the case of the E^2 = (mc^2)^2 + (pc)^2?
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    Time Dilation homework

    Because relative to itself a beam of light would travel there and back in a shorter amount of time than the spaceship. I guess i was thinking of the beam of light relative to time on earth rather than to itself.
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    E=mc^2 question

    so using the expression that Ben gave me I would solve for p then? Edit: Or if i wanted to continue on my original path i would solve for v and then plug that into the equation for relative momentum, and solve for it in terms of mc. i calculate the v to be v= 0.97c p= mv/(square...
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    Time Dilation homework

    So even though a photon of light would take ten years to get there and ten years to get back.. a total of 20 years. I guess it just seems weird to me that, unless i am thinking about this the wrong way, it would take longer for a beam of light traveling at the speed of light than this spaceship.
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    Relativistic density

    More than likely it is the relativistic mass. In which case i would need to solve for the relative mass of the particle while moving at .9c as well as the contraction factor of the cube.. 2000/square root(1-0.9^2)= 4588.31 kg and the calculated relative dimensions of the cube were calculated...
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    Relativistic density

    I think i forgot to square my velocity initially. The answer should be 2000 kg/ .436m^3 or 4588.31 kg/ m^3?
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    Time Dilation homework

    So then i would take this velocity and put it into my original equation and solve for deltaTprime.... When i do this i get a time value of 15 years, using 25 years as the deltaT. Then I would add one year to that for the time that was spent on the other planet? So their chronometers would read...
  10. X

    Time Dilation homework

    Oh right because its 10ly away from earth ... Ok that makes sense. Thank you.
  11. X

    E=mc^2 question

    What is the momentum of a particle whose total energy is four times its rest energy? Give your answer as a multiple of mc. Well the rest energy of an object is E=mc^2 so the total energy for this particle would be E= 4(mc^2) in order to achieve this Energy value the Lorentz factor would...
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    Time Dilation homework

    hmm it seems odd that the time on earth would give you a correct value for the velocity considering that the distances would change when approaching such great speeds.
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    Time Dilation homework

    so i wouldn't use that equation then for part a. I would just take 20 ly/25 yrs? (20*3*10^8)/(25)= 2.4 * 10^8 2.4/3= 0.80 v= 0.80c
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    Relativistic density

    A cube has a density of 2000 kg/m^3 while at rest in the laboratory. What is the cube's density as measured by an experimenter in the laboratory as the cube moves through the laboratory at 90% of the speed of light in a direction perpendicular to one of its faces? It's the dimensions of the...
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    Time Dilation homework

    A starship Voyages to a distant planet 10 ly away. The explorers stay 1 yr, return at the same speed, and arrive back on earth 26 yr after they left. Assume that the time needed to accelerate and decelerate is negligible. a) What is the speed of the starship? b) How much time has elapsed on...
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    Rate at which energy is dissipated

    :frown:Please help me out. Thank you.
  17. X

    What is the voltage? AC circuit

    :uhh:Please help me out. Thank you.
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    What is the coils inductance?

    :confused:Please help me out. Thank you.
  19. X

    Resonace frecuency and peak current

    Please help me out. Thank you.:cry:
  20. X

    Inductance and current

    Please help me out. Thank you.
  21. X

    Inductance and current

    An RLC circuit consists of a 48 ohm resistor, a 200 uF capacitor, and an inductor. The current is 2.5 A rms when the circuit is connected to a 120 V/60 Hz outlet. a. What is the inductance? b. What would be the current if this circuit were used in France, where the outlets are 220 V/50 Hz...
  22. X

    Resonace frecuency and peak current

    For the circuit shown a. What is the resonance frequency? b. At resonance, what is the peak current through the circuit? http://img218.imageshack.us/img218/2971/p56dr3.png [Broken] I solved for resonance frequency knowing that when Xc=XL you get a resonance frequency. my set up was...
  23. X

    What is the coils inductance?

    A coil has a resistance of 2.10 ohms. The potential difference across the coil is 11.6 V at an instant when the current through the coil is 5.00 A and is decreasing at a rate of 36.0 A/s. What is the coils inductance? I thought i could use the equation X=2pi fL to solve for L.. but i am...
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    What is the voltage? AC circuit

    A 60 Hz power source with a peak voltage of 12.0 V is connected to a resistor. At a particular instant the voltage across the resistor is 10.0 V and decreasing. What is the voltage 1.5ms later. I tried using the equation v= V cos(2 pi ft) v= 12.0V cos(2pi (60Hz)(1.5 X 10^-3s)) v= 10.13...
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    Rate at which energy is dissipated

    Light bulbs labeled 40W, 60W, and 100W are connected to a 120V/60Hz power line as shown in the figure. What is the rate at which energy is dissipated in each bulb? http://img156.imageshack.us/img156/9584/p41qz1.png [Broken] Well ac circuits has been confusing me. I first though if a light...
  26. X

    A conducting loop around a magnetic field

    So even though the field is not changing position relative to the wire there is still an induced current.. hm well the flux is changing.. it is increasing as the magnetic field increases. so yes the bulbs would light up(because of what you have said) and i would assume that they would be of the...
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    A conducting loop around a magnetic field

    A conducting loop around a magnetic field contains two light bulbs. as shown int the figure. The wires connecting the bulbs are ideal. The magnetic field is increasing rapidly. A. Do the bulbs glow? why or why not? B. If they glow, which bulb is brighter? or are they equally bright? explain...
  28. X

    What current will allow the wire to float ?

    so then i can set that force equal to the force between the wires and solve for I. I get a value of 49kA when i do this.. this seems like a lot but it would also seem that an enormous amount of current would be needed to overcome the force of gravity. let me know what you think.
  29. X

    What current will allow the wire to float ?

    Please Help me out. I am missing something but i cant seem to connect the dots
  30. X

    Electron traveling through two parallel charged plate. What is Magnetic Field?

    being that you say it is not essential, i am confused as to how i would then arrive at a value for the b-field that does not contain some variable. This is from a non calculus based class so try not to make it to complicated for me :)
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