When Object 1 came into contact with Object 2 and Object 2 got warmer, what can be inferred about the objects before contact?

When Object 1 came into contact with Object 2 and Object 2 got warmer, what can be inferred about the objects before contact?

• A. Object 1 had faster-moving particles.
• B. Object 2 did not have thermal energy.
• C. Object 1 had less thermal energy.
• D. Object 2 had fewer particles.

Answer: (A)

Heat flows from the warmer object to the cooler one when they touch, until both reach the same temperature. If Object 2 gets warmer, energy moved into it, so Object 1 must have been hotter just before contact. A hotter object has particles moving faster on average, so Object 1’s particles were moving faster than Object 2’s before they touched. The other ideas don’t fit: any real object at a nonzero temperature has some thermal energy, so Object 2 certainly had thermal energy. If Object 1 had less thermal energy, it wouldn’t be the source of the heat. The number of particles isn’t the determining factor here; heating depends on temperature difference and the masses/heat capacities involved.

Heat flows from the warmer object to the cooler one when they touch, until both reach the same temperature. If Object 2 gets warmer, energy moved into it, so Object 1 must have been hotter just before contact. A hotter object has particles moving faster on average, so Object 1’s particles were moving faster than Object 2’s before they touched.

The other ideas don’t fit: any real object at a nonzero temperature has some thermal energy, so Object 2 certainly had thermal energy. If Object 1 had less thermal energy, it wouldn’t be the source of the heat. The number of particles isn’t the determining factor here; heating depends on temperature difference and the masses/heat capacities involved.