If you throw a hot rock into a pail of cool water, you know
that the temperature of the rock will go down. You also know that the
temperature of the water will go up—but will its rise be more than, less than,
or the same as the temperature drop of the rock? Will the temperature of the
water go up as much as the temperature of the rock goes down? Will the changes
of temperature instead depend on how much rock and how much water are present
and how much energy is needed to change the temperature of water and rock by
the same amount?
You are going to study what happens to the temperature of
water when hot or cold washers are added to it. Before doing this activity,
think about the following questions.
that equal masses of water and iron are at the same temperature. Suppose you
then add the same amount of heat to each of them. Would one change temperature
more than the other?
you circled “yes,” which one would warm more?
suppose that equal masses of water and iron are the same temperature. Suppose
you then take the same amount of heat away from each of them. Would one cool
more than the other?
you circled “yes,” which one would cool more?
STEP 1: Find the mass of 30 washers using the digital scale.
Knowing what you know about density, figure out how much cold water you will
need to equal the mass of the washers (hint, density of water is 1g/mL).
STEP 2: Pour the appropriate amount of ice-cold water into a
STEP 3: Place your washers into the “washer heating water”
that the teacher has set up for you. Leave the washers in the water for at
least 2 minutes to allow them to reach an equilibrium temperature.
the temperature of the hot water equal to the temperature of the washers? Why
do you think it is or is not? Can you think of a better way to heat the washers
to a known temperature?
that you have equal masses of water and washers at the same temperature.
Suppose you then light similar candles and place a candle under each of the
masses, letting the candles burn for equal times. Would one of the materials
change temperature more than the other?
you circled “yes,” which one would reach a higher temperature?
you have cold feet when you go to bed, and you want something to warm your
feet. Would you prefer to have a hot-water bottle filled with hot water, or one
filled with an equal mass of washers at the same temperature as the water?