Solutions to Concept Survey: Heat
1. When two systems are in thermal equilibrium, they have
(a)
(b)
(c)
(d)
(e)
the same internal energies.
the same pressures.
the same volumes.
the same temperatures.
the same entropies.
2. 20 grams of metal X at temperature 300K are placed in 20 grams of fluid Y which is at 250K. If X has a
higher specific heat than Y, the equilibrium temperature will be
(a) 250K
(b) between 250 and 275K
(c) 275K
(d) between 275 and 300K because the substance with the higher specific heat changes less in
temperature, all else being equal
(e) 300K
3. If I mix 100 grams of water initially at 20 oC with 200 grams of water which is initially at 80 oC, what
will the final temperature be?
(a)
(b)
(c)
(d)
(e)
50 oC
between 50 oC and 80 oC because the larger quantity of water has a greater heat capacity.
between 20 oC and 50 oC
20 oC
80 oC
4. I have two solid metal rods, one meter long. One rod has twice the diameter of the other. Which rod
is a better conductor of heat?
(a) the thinner one
(b) the wider one
(c) they will be the same.
5. The primary way in which gases (such as air) transfer heat energy is
(a)
(b)
(c)
(d)
(e)
conduction
radiation
convection
calorimetry
evaporation
6. If I take an ice cube out of the freezer, it will initially have a temperature of -20 oC. If I set it in a dish
on my table, it will warm up until it reaches 0 oC, and then
(a)
(b)
(c)
(d)
its temperature will continue increasing as it also melts
it will melt but stay at 0 oC. There is no temperature change until all the ice has melted.
it will melt and its temperature will decrease.
it will increase in temperature but will not start melting yet.
7. The primary mode by which the sun gives energy to the earth is
(a) conduction
(b) radiation
(c) convection
(d) calorimetry
(e) evaporation
8. This question was erroneous and has been trashed.
9. I place two beakers of water in the sun. Each has 100 ml of water and they start out at room
temperature. If I dissolve black ink in one beaker of water, what can you say about the temperatures of
the two beakers after a short while?
(a) the black water will be hotter Black is a better absorber of heat
(b) they will have the same temperature
(c) the black water will be cooler.
10. At a higher temperature, the molecules in a metal are
(a)
(b)
(c)
(d)
larger in size
smaller in size
moving faster
moving slower