A2L Item 091

• Description: Identify the correct statements regarding the energy of and heat flow between two bodies.
• Goal: Hone the concept of internal energy and heat.
• Source: UMPERG-ctqpe180
• Keywords: Energy, Temperature, Thermodynamics

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The question for students:

Body A has a higher temperature than body B. Which of the following statements is true?

1. Body A will feel hotter than body B.
2. Body A contains more energy than body B.
3. If placed in contact with each other, energy will flow from body A to body B.
4. If placed in contact with a third body having temperature greater than body A, body B will absorb more heat than A.
5. More than one statement is true.

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Commentary for teachers:

Answer

(3) Only statement (3) is always true. Placed in contact, heat will flow from the higher temperature body to the other regardless of the masses of the bodies.

The ‘feel’ of a body’s temperature depends upon the material and the rate of heat conduction. Body A could be much smaller than body B and, therefore, contain much less energy than body B even though at a higher temperature. Likewise, if body B is smaller it can absorb less energy from a third body than body A even though it has a lower temperature.

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