• Question: How is heat able to put molicules in motion?

    Asked by ÉmíNGP2511 to Gavin, Karen, Mark, Michel, Roisin on 12 Nov 2016.
    • Photo: Mark Kennedy

      Mark Kennedy answered on 12 Nov 2016:

      So when you’re heating something, you’re putting energy into that system.

      Imagine you have some gas above a Bunsen burner. The flame form the Bunsen burner is thermal energy, and that thermal energy is converted into kinetic energy in the gas.

      Since the kinetic energy of anything can be calculated using

      E=0.5 m v*v

      Where E is energy, m is mass and v is velocity, then you can see that is we increase E while keeping m constant, then v (which is the velocity of your molecules) must increase.

      So transferring any energy into molecules causes them to move faster, since their velocity must increase. Make sense?

    • Photo: Roisin Jones

      Roisin Jones answered on 13 Nov 2016:

      Nice answer Mark! The only thing I’d add is that the reason that energy must be converted from heat to movement is because we can’t destroy energy, it can only be changed from one form into another (as per the law of conservation of energy). Since they can’t destroy it, the only way the molecules have of using the energy from the heat is to change it into kinetic energy, i.e. start moving about!

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