AP® Physics 1 & 2

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Conduction vs. Convection Experiment

APPH12-EJZLGN

A group of physics students is trying to investigate which method of heat transfer, convection or conduction, is most responsible for the cooling of a hot beverage. The students fill two identical paper cups with hot water ($100^\circ \text{C}$). One cup has a thick insulating lid and the other does not have a lid. The cups are left in a large room at $23^\circ \text{C}$. After twenty minutes the students measure the temperature of the water in the cups. The cup with the lid was $85^\circ \text{C}$. The cup without the lid was $79^\circ \text{C}$.

Based on this evidence alone, what can the students conclude about the energy lost by convection and conduction and why?

A

Convection is a faster method of heat transfer than conduction. The cup without the lid had a lower final temperature.

B

Conduction is a faster method of heat transfer than convection. The cup with the lid suffered a $15^\circ \text{C}$ change in temperature, and that is more than the difference of $85^\circ \text{C}$ and $79^\circ \text{C}$.

C

The data are inconclusive. The students need another trial with a paper cup that is well insulated on the sides, but without a lid, to track the heat lost through conduction.

D

The data are inconclusive. The students need to monitor the two cups of water all the way until they reach thermal equilibrium with the room.