Download Shaky Water

NAME ________________
PER____
DUE DATE ______
MAIL BOX_____
Shaky Water
Can we change the energy in a bottle of water using nothing but our hands?
Define: the Law of Conservation of Energy (write it in full) -
Define: Energy Transformation -
1. What kind of energy did you use to shake the water? Circle one
a. Muscle power: kinetic energy.
b. shaking power: joules
c. thermal power: kinetic energy.
d. thermal: potential energy.
2. List at least three energy transformations in order that occurred during this experiment.
3. What does temperature ultimately really measuring? One or two word answer will do.
4. Explain how this activity demonstrated the concept of energy conversion and transformation. Be
descriptive, discuss energy types.
5. Discuss whether this was an efficient method of energy transformation. Answers should discuss the
waste energy that did not get transferred to the water and where else did the energy go?
Phy Sci 2016
NAME ________________
PER____
DUE DATE ______
MAIL BOX_____
Procedure
1. Fill the container about one-third full with room temperature water.
2. Measure the volume of water by pouring it into a graduated
cylinder. Since one cubic centimeter of water weighs one gram, you
know exactly how much your water weighs.
3. Measure the temperature.
4. Then put the lid on tightly.
5. Shake the bottle vigorously for two minutes, then record temperature again.
6. Pass the bottle let the next lab partner shake.
Data Table
Time (min)
0 min
2min
4min
6min
8min
10min
12min
Temperatures
Celsius
BACK GROUND
It turns out that we can indeed change the overall thermal energy state of a bottle of water with
nothing more than our hands and some vigorous shaking. We can in fact convert potential energy stored
in our muscles into kinetic energy, which is transferred into the water as thermal energy as the result of
the friction of the molecules bumping against each other and the sides of the container. The heat
energy in the water is not “created”, rather it is transferred from your muscles, which have stored
energy from food, which ultimately is received from the sun. The inefficiency of the energy conversion
(from muscle power to heated water) becomes evident through the generation of “waste” heat: the
shakers get warm, and they may even start to perspire.
Phy Sci 2016
NAME ________________
PER____
DUE DATE ______
MAIL BOX_____
Relate the rise in temperature to the amount of energy that entered the water. A calorie is defined as the amount of
energy needed to raise the temperature of one gram of water by one degree Celsius.
Degrees of temperature rise (C) X volume of the water (g) = calories
Food Calories Versus Energy Calories and Inefficiencies of Energy Transfers
A food calorie (which is sometimes spelled with a capital “C”) is 1,000 times larger than an energy calorie (which is
always spelled with a lower case “c”).
If 300 calories of energy went into the water, that is the equivalent of .3 food Calories. The ratio of energy used over
energy expended represents the efficiency of the operation, so if your body actually used 3 food Calories to add 300
calories to the water, the operation would be 10% efficient. (3 X 1,000) ÷ 300 = 10%) A great deal of wasted energy went
into the students’ bodies (which they felt as a warming up in their arms and muscles), and other heat energy was
released to the room from the students’ bodies as their heated muscles were cooled by the air.
Extenders 1. Have students vary the types and sizes of the containers, as well as the fullness of the container. Find an
optimum level and container type, then discuss possible reasons for the variation. (You will find that smaller volumes of
water heat up better, so the container should not be too full, and harder containers yield better results than softer
containers.) Background Science Students may have heard of the “Law of conservation of energy,” which states that
“energy is not created or destroyed. Energy may be transformed from one kind into another, but its total magnitude
remains the same.” Even when energy seems to explode out of nowhere, as in lightning or fireworks, the light and heat
energy is really being transferred from other forms of stored energy. The energy that went into the lightning was stored
as electrical charges in the atmosphere. The energy that went into the fireworks display was stored in the chemicals in
the firecracker. When lit, the chemicals released that energy in the form of light and sound. Energy comes in many
different forms. In addition to heat (thermal energy) and light (radiant energy), there is also electrical energy, chemical
energy, and physical (kinetic) energy. All energy derives ultimately from the sun, and it is transferred through many
processes. The sun, for example, heats up the atmosphere to create wind and drive the water cycle. Plants convert
energy from the sun and store it chemically as starch. Animals consume the starch and transform that stored energy into
heat energy, kinetic energy, electrical energy (in our neurons), and even chemical energy (from our excrement). In this
activity, students transfer some of their potential chemical energy into kinetic energy, where it quickly becomes thermal
energy.
Phy Sci 2016