1. Question Details Walker3 16.CE.002. [612802]
Referring to Table 16-1, which would be more accurate for all season outdoor use, a tape
measure made of steel or one made of aluminum?
steel
mc
aluminum
Key: The steel tape measure would be better because its coefficient of thermal expansion
is smaller. This means that its length would change less with temperature.
2. Question Details Walker3 16.CE.010. [612634]
Two objects are made of the same material but have different temperatures. Object 1 has
a mass m, and object 2 has a mass 2m. If the objects are brought into thermal contact, is
the temperature change of object 1 greater than, less than, or equal to the temperature
change of object 2?
mc
greater than
less than
equal to
Key: The less massive object, which has the smaller heat capacity, will have the greatest
change in temperature. Thus, the temperature change of object 1 is greater than the
temperature change of object 2.
3. Question Details Walker3 16.CE.018. [612579]
Two bowls of soup with identical temperatures are placed on a table. Bowl 1 has a metal
spoon in it; bowl 2 does not. After a few minutes, is the temperature of the soup in bowl 1
greater than, less than, or equal to the temperature of the soup in bowl 2?
greater than
less than
mc
equal to
Key: The soup with the metal spoon in it has the lower temperature; that is, the
temperature of the soup in bowl 1 is less than the temperature of the soup in bowl 2. This
is mainly due to the fact that heat conducts readily from the soup into the metal spoon,
and from the spoon into the cool surrounding air. The spoon also absorbs a small amount
of energy from the soup, assuming the spoon was at a lower temperature than the soup
when it was inserted.
4. Question Details Walker3 16.CQ.020. [614118]
The fur of polar bears consists of hollow fibers. (Sometimes algae will grow in the
hollow regions, giving the fur a green cast.) Explain why hollow hairs can be beneficial
to the polar bears.
Key: The hollow fibers of hair are effective insulators because the gas within the fibers
has a low thermal conductivity. This is analogous to double-pane windows, which trap a
layer of gas between the panes for a greatly enhanced insulating effect.
5. Question Details Walker3 16.CQ.014. [613910]
When you touch a piece of metal and a piece of wood that are both at room temperature,
the metal feels cooler. Why?
Key: Both the metal and the wood are at a lower temperature than your skin. Therefore,
heat will flow from your skin to both the metal and the wood. The metal feels cooler,
however, because it has a greater thermal conductivity. This allows the heat from your
skin to flow to a larger effective volume than is the case with the wood.