As I understand it thermal energy (heat) is simply a measure of the kinetic energy of an object (For example : water).Hot water is simply water with a larger kinetic energy in its molecules, right ? So how do my hands get burned if I immerse them in hot water ? Do the particles collide with my hand and produce burns ? PS : I may have a conpletely wrong understanding of how heat works .

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    $\begingroup$ Yes that is correct, the molecules of water transfer kinetic energy to your skin molecules and deeper, the skin molecules get damaged very quickly releasing chemicals that trigger the pain response in nerves. Not pleasant and not good for your body as it gets opened up to infection. $\endgroup$ – PhysicsDave Oct 28 '18 at 14:16
  • $\begingroup$ @PhysicsDave Thank you. What about a gas at room temparature . The kinetic energies of molecules are higher right . So why don't we get burns. Or is it not necessary that a higher phase has more kinetic energy ? $\endgroup$ – A.R.K Oct 28 '18 at 14:26
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    $\begingroup$ Temperature is a measure of the average kinetic energy of particles in a substance. Air particles at room temperature would have the same average EK as water particles at room temperature. $\endgroup$ – M. Enns Oct 28 '18 at 19:44
  • $\begingroup$ Gases tend to have lower masses and higher velocities so 0.5mv^2 is satisfied for a gas at room temp at 20C. $\endgroup$ – PhysicsDave Oct 29 '18 at 3:15

Yes, temperature is generally a measure of the average translational kinetic energy of the molecules of an object.

Skin burns occur when the combination of the temperature on the skin and the duration of the exposure of the skin to that temperature exceed the threshold of burn.

Given a solid, liquid (e.g. water), and gas at the same temperature in contact with the skin, a burn will generally occur first (in time) with the solid, followed by the liquid, and then the gas, due to the relative heat transfer rates (conduction and convection).

So yes your skin can get burned due to exposure to water as well as a gas. It will be less severe if you are in contact for the same amount of time with a gas than than with the water, but more severe if you were in contact with a solid at the same temperature,

Hope this helps


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