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# Thermal equilibrium- Thermometer measuring a container of water(physics question) Watch

1. So, a thermometer is placed into a container of water that has been heated. Now if the thermometer is placed in the water, then in actual fact, has the thermometer measured the true value of the temperature of the water?

As Kinetic energy is being shared by the thermometer due to the moving particles that make up the water.

So if this is the case how do we measure how much kinetic energy has been shared?

If the water is heated to say 50 degrees, then in order for their to be thermal equilibrium, donot the mercury particles in the thermometer have to be at the same temperature, and so would not the water particles lose all of their energy when they're sharing it with the thermometer?

Thank you
2. (Original post by sulexk)
and so would not the water particles lose all of their energy when they're sharing it with the thermometer?

Thank you
The water particles would not lose ALL of their energy, just enough such that the temperature of the water is the same as that of the thermometer. Because the mass of water is most likely to be much greater than that of the thermometer the loss of heat of the water is negligible.
3. So if this is the case how do we measure how much kinetic energy has been shared?
As Sam1AM said, the transfer of KE is negligible as the thermometer has a very small specific heat capacity(SHC) to serve its purpose.

If you want to know the transferred energy, just find the mass of the thermometer, change in temperature and its SHC and multiply all together.

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Updated: December 25, 2010
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