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  1. J

    How to calculate surface temperature of earth?

    Assumption: Earth is a perfect blackbody. This means that the emissivity (ε) is 1. Earth’s radius = 6371 km Incident solar radiation = 1367 W/m2 Temperature in space = 0 K I'm given the above data. I tried using the E= σεTe4 but that doesnt include the radius of the Earth :S Im really...
  2. J

    How do you convert BTU/lbF into J/kgK?

    I know 1BTU = 1055J 1lb = 1/2.2046 kg 1 F = 255.928 K then 1 BTU/lbF should be 1055/(1.2046)*255.928. But I get 9 plugging this in the value is suppose to be 4186 J/kgK. this is the specific heat of water
  3. J

    Why is the nominal capacity of power plants given in terms of power, not energy?

    Why is the nominal capacity of power plants given in terms of power and not in terms of energy?
  4. J

    Help me with some motors and generators Q

    Help me with some motors and generators Q!! We are learning about motors and generators But I got completely lost when we started talking about Michael Faraday's work, Electromotive force, Electromagnetic induction, Lenz Law I get what Michael Faraday did, applying force to a...
  5. J

    Are there any Cons in using rotational speed of Earth for Rockets?

    I have 2 advantages of using rotational and orbital velocity of Earth in assisting easier rocket travel... 1. Uses less fuel as the rotational speed contributes to the rocket 2. Assists the rocket to easily produce the necessary escape velocity Are there anymore adv??? I can't seem to...
  6. J

    Conventional current vs current?

    I was always taught that current was the flow of electrons, a direction which negatively charged particles flow but now we started to talk about conventional current where the positive particles are flowing.. I'm so confused... what specific positive charge is flowing?? and how come people...
  7. J

    Has General relativity been proven wrong ?

    I'd like to know whether the concept of space-time still exists today My physics teacher doesn't like to believe gravity in relation to space-time
  8. J

    Why is light the fastest ?

    Why is light the fastest ?? I don't get why nothing can be faster than light. I know Einstein postulated that speed of light is constant and mass increases and energy increase. But I am still confused as to why nothing can't exceed speed of light
  9. J

    Major difference of Inertial and non-inertial frame of reference ?

    Major difference of Inertial and non-inertial frame of reference ?? What is the major difference or differences of Inertial and non-Inertial frame of reference?? Is it only: Inertial - Constant velocity, obeys the law of inertia Non-inertial - Acceleration, disobeys the law of inertia
  10. J

    What does relative mean

    What does relative mean..!! I still don't understand the meaning of relative. I cannot breach onto the concept of Einstein's Principles of Relativity without knowing the meaning of it!!! I searched the internet but all of the definitions listed makes no sense to me.. Can somebody...