1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Equating Heat and Einstein's equation confusion

  1. Dec 5, 2013 #1
    I should start by saying that I am a bit embarissed by asking such a silly question
    By simply equating the mass-energy formula with the temperature dependence of heat...

    M*c2 = M* cm *ΔT

    it strikes me as odd that the mass cancels,

    c2 = cm *ΔT

    I was doing this in order to calculate how much mass is gained by heating say a cup of water up by a specific amount (I know it would be very small, but I was just curious of the order of magnitude). But it seems I cannot do this, so there must be something obvious I am missing.
  2. jcsd
  3. Dec 5, 2013 #2


    User Avatar

    Staff: Mentor

    They don't cancel because they are two different masses. On the left is the mass equivalent of the energy and on the right is the rest mass of the water.
  4. Dec 5, 2013 #3


    User Avatar
    Science Advisor
    Gold Member

    ...or to put it another way, the equation should be
    [tex]\Delta m \, c^2 = m \, c_m \, \Delta T[/tex]
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Equating Heat and Einstein's equation confusion
  1. Heat equation (Replies: 3)

  2. Einstein work equation (Replies: 0)

  3. The heat equation (Replies: 19)

  4. Heat Equation (Replies: 3)