Download Mechanical Energy = Potential Energy + Kinetic Energy

Name__________________________________J# _______
Energy Transfer (Conversion)
TESTABLE QUESTION
By applying mechanical energy to sand, can you change the overall temperature of sand (thermal energy)?
RESEARCH/BACKGROUND
The ability to do work is called energy. Work, therefore, occurs when energy is changed from one form to
another. There are many forms of energy.
Mechanical energy, as you know is the energy associated with the motion (kinetic) or position (potential) of an
object. The terms kinetic and potential, when written or stated simply as kinetic and/or potential, the reference
is to mechanical energy. Therefore, if you see the words potential or kinetic alone, without the energy type
written with it, you can assume it is referring to mechanical energy. It is important to understand that all other
types of energy involve potential and kinetic energy also. However, when written in reference to another form
of energy (chemical, thermal, electrical, electromagnetic, or nuclear), it will be clear. For example, the
chemical potential energy in food is what gives us the ability to do work.
Chemical energy is stored (potential) in the bonds of molecules (atoms), such as in the foods we eat, batteries,
or any kind of fuel (coal, oil, gas, wood).
Thermal energy is the total kinetic energy of the particles of an object (heat), such as melting ice cream due to
the hot air. Temperature is a measure of the amount of kinetic molecular movement. Thermal energy is
transferred in 3 ways: Radiation, Convection, and Conduction *see your Cornell notes!
Electrical energy is the energy of electrical charges (kinetic-movement of electrons), such as the energy from
electrical lines, or lightning.
Electromagnetic energy travels (kinetic) in waves. These waves have some electrical properties and some
magnetic properties. Examples, in increasing order of amounts of energy are: radio waves, microwaves,
infrared radiation, sunlight (or visible light), ultraviolet, x-rays, gamma rays
Nuclear energy is energy stored (potential) in the nucleus of an atom. It is released with either the atoms split
(nuclear fission—used in nuclear power plants) or the atoms come together or fuse (nuclear fusion—what
occurs in the sun and other stars releasing tremendous amounts of energy).
Any form of energy can be changed into any other form. This change is known as an energy conversion. The
Law of Conservation of Energy states that energy cannot be created or destroyed. The total amount of
energy, therefore, is the same before and after an energy conversion; however, the amount of useful
energy decreases (there is some wasted or exerted on outside factors).
HYPOTHESIS
Make a statement that answers the testable question above.
__________________________________________________________________________________________
__________________________________________________________________________________________
MATERIALS
16 z plastic bottle with lid
plastic funnel
Celsius thermometer
fine dry sand (approx. 500 mL)
tray or tub to collect sand spills
goggles
calculator
colored pencils for graph
PROCEDURE—Partner up
1. Using the funnel, fill the plastic bottle ½ full with sand. Do this over a tray or tub to minimize the amount
of spillage.
2. Carefully place the bulb of the thermometer in the sand (about an inch or 2.5 centimeters).
3. Wait two minutes; then measure the temperature of the sand and record it in the data table.
4. Cap the bottle tightly and shake it vigorously for exactly five minutes. If you get tired, pass it around to
your lab partner to take turns.
5. Repeat steps 2 and 3.
6. Get new sand in the bottle and repeat steps #1-5 for two more trials.
7. **Honors---While you are shaking, complete the additional data table (attached)—Celsius/Fahrenheit
conversions.
SAFETY CONCERNS
Wear goggles. Clean up any spills; sand can make the floor very slippery. If sand gets in your eyes, inform me!!! Use
caution to avoid injuries.
OBSERVATIONS/GATHER DATA
Average (mean value) = (T1+T2+T3)÷3
Uncertainty= (Highest Trial-Lowest Trial)÷2 *How off could you be or uncertain are you?
True Value Range = Average – Uncertainty (bottom range) and Average + Uncertainty (top range)
*Your precise value lies within this range. Human error contributes to this.
Shake Times
Start
After five
minutes of
shaking
Temperature(degrees C)
Average Uncertainty
oC
oC
Trial 1
oC
Trial 2
oC
Trial 3
oC
20
21
20
20.3
.5
24
24.5
25
24.5
.5
True Value Range oC
19.8-20.8
24.0-25.0
ANALYZE DATA /GRAPH
Make a graph for the averages…(is this continuous data or is the data you are collecting discrete?)
Graph type BAR
*Don’t forget your graph title, axis titles, units, and BE NEAT!
Average Temperature of 3 Trials (Celsius)
How shaking a bottle of sand for 5
minutes affects the average
temperature (amount of kinetic thermal
energy) in the sand.
30
25
20
15
10
5
0
24.5
20.3
Start Time (0 Minutes)
After 5 minutes
Time (Minutes) mechanical energy was added
CONCLUSIONS
The PURPOSE of this
experiment was to show that energy can be converted one type to
another (mechanical to thermal). My hypothesis, if the amount of
mechanical energy given to a bottle of sand increased, then the
thermal energy inside the bottle would increase b/c the mechanical
1. Write a Conclusion. Purpose, hypothesis, supported? Data…
energy would convert into thermal energy (more shaking = hotter
sand) was supported because the starting temperature of the sand
averaged 20.3 degrees Celsius and the ending temperatures (after 5
minutes of shaking) averaged higher (24.5 degrees). There was no
overlapping of temperature in my true value ranges (DATA)
(starting temperature = 19.8-20.8 degrees Celsius, and after 5
minutes = 24-25 degrees Celsius). This showed that my precise
value before shaking was definitely lower than after shaking for 5
minutes. Thus proving that by adding mechanical energy to sand
(shaking) the amount of heat measured (temperature) increased.
There is a relationship between the amount of mechanical energy
added to a substance and the amount of thermal energy after the
transfer.
What was your test variable:
Amount of mechanical energy (quantified by
shake time).
Outcome variable: Amount of heat (temperature).
3. What did you hold constant to make sure your test was a valid one?
SHOULD HAVE held constant the amount of sand, amount
of shaking time, placement of thermometer, person shaking,
shaking speed. However, this was not necessarily the case.
Your experiment had some validity issues, but your data was
consistent enough to say that those constants had some
flexibility.
EVALUATION/ANALYSIS
1. Would changing the amount of sand used change the results? Why or why not?
Varying Thoughts
2. Would changing the size of the container used change the results? Why or why not?
Varying Thoughts
3. What kind of energy was contained in the sand after shaking? Explain. Don’t just write one word.
Thermal—Thermal energy is heat energy. The bottles were
hotter after they were shaken. *However, there was thermal
energy in the sand before….there is just MORE now.
4. This experiment showed a transfer of energy. Show with a flow chart the transfer of energy from one type
to another that occurred here. Place the event that took place in the boxes and the energy type on the lines
below.
Food
Chemical
Arm Moving
Back and
Forth
Mechanical
Sand moving
Sand warms
(Friction)
Mechanical
Thermal
5. Did all of the first type of energy you applied to the sand transfer to the second type of energy you
measured? Meaning….was any energy wasted? Why or why not? Explain.
YES ---some was lost to the bottle (Thermal (warm bottle)
and Mechanical (vibrations)), to the air (Mechanical-Sound
and Thermal to air)