1. Shooting Rubber Bands Overview
For this introductory activity you will shoot rubber bands stretched to various distances.
Hypothesis: ?
Materials:
Rubber Band
Ruler
Data Table
Procedures:
Write a hypothesis in your composition that states your guess as the the effect that the distance a rubber band is stretched has on the distance the rubber band will fly.
Place a rubber band on the edge of the ruler, pull it back to 10 cm, and release the rubber band. Be sure the ruler is parallel to the floor.
Measure the distance traveled by the rubber band and record it in a data table.
Repeat these steps while increasing the distance the rubber band is pulled back by five centimeters for each release.
Average your results and create a line graph of your average data with distance traveled on the y-axis and the distance you pulled the rubber band back on the x-axis.

2. QOD :
Today, we will do an experiment that tries to answer the question: What variables affect the speed of a pendulum.
1. Spend 5 minutes reading the first page of the handout and write down your guess regarding what affect shortening the length of a pendulum will have on the speed of the pendulum

3. QOD:
On Friday, we did an experiment that tries to answer the question: What variables affect the speed of a pendulum?
We tested how changing the length of the string affected the speed of the pendulum.
1. What did your data show regarding this question?
2. What affect do you think increasing the weight of the pendulum will have on the speed of the pendulum?

4. QOD
Last Friday we did an experiment to see what variables affect the speed of a pendulum
1. Reread your hypothesis
2. Write a hypothesis that addresses the following question:
Does the height from which you drop the pendulum affect the number of swings in 10 seconds?

5. Data Table
Trial
10 cm
15 cm
20 cm
25 cm
30 cm 1 2 3
Average

6. Questions What patterns or trends did you notice?
Was energy used to launch the rubber band? If so, explain your reasoning.
What factors could have impacted the accuracy of your data?
Did your data support your hypothesis? Explain your reasoning.

7. Energy Today, we will begin our study of energy.
List 3 things that you know about energy
List 3 things that you would like to learn about energy or things that you wonder about.

8. Energy

9. Energy the ability to do work or cause change
measured in units of joules (J)
two general types of energy:
Potential
Kinetic

10. Work
Work is done when an applied force causes an object to move in the direction of the force
Units of joules (J)
Formula: Work = Force x distance
What are some
examples of work being done that fit this definition?
W = (F)(d)
Sample Problem
Three students push on a car with
100 N of force and the car moves 10meters.. How much
work did the students perform in? =
(100N)
(10 m) =
1000 N•m or 1000 J
Eureka video on work

11. Work problems: Work=(Force)(Distance)
You push a refrigerator with a horizontal force of 100N. If you move the refrigerator a distance of 5meters, how much work do you do?
W=Fd
F=100N
d=5N
W=(100N)(5M)
You do 500Joules of work

12. Work problems:
How much work do you do when you lift a 100N child 0.5meters?
W=Fd
F=100N
d=0.5meters
W=(100N)(0.5meters)
You do 50joules of work

13. QOD
1. How much work do you do if you lift a 9N book 1.7 meters over you head?
2. How many meters over your head do you have to lift a 5N book to do 2.5 J of work?

14. Potential Energy (PE)
stored energy that an object has due to its position or its chemical composition
Types of potential energy:
Gravitational Potential Energy – results from how high an object is above the earth.
Formula: GPE = (mass)(gravity)(height)
Elastic Potential Energy – results from stretching or compressing.
What is an example of something that stores energy when it stretches or compresses?
Chemical Potential Energy- Energy stored in chemical bonds.
What is an example of energy stored in a chemical?
0.45 kg
Which soccer ball has more gravitational
potential energy? Explain your reasoning.

15. Potential energy question
The higher an object is above the earth, the more gravitational potential energy it has.
On your white board, draw the path you would take if you were to swing on a playground swing. label the point of highest GPE and the point of lowest GPE.

16. Which soccer ball has more kinetic energy? Explain your reasoning.
Kinetic Energy (KE)
energy of motion
depends on mass and velocity
Formula: KE = ½ (mass)(velocity)2
KE increases as mass or velocity increases and decreases as mass or velocity decreases
2 m/s
3 m/s
0.45 kg
Which soccer ball has more kinetic energy? Explain your reasoning.

17. Kinetic energy question
The faster an object moves, the more Kinetic Energy it has.
1. On your white board, draw the path that your swing took yesterday and label the point of highest kinetic energy and the point of the least kinetic energy

18. Relationship Between PE and KE
What is happening to the PE and KE as the soccer ball falls to the feet of the mid-fielder?
PE KE
What about the PE/KE graph could be considered misleading?

19. Practice Problems
A diver weighing 46 kg is preparing for a dive from the 10 meter diving platform. How much gravitational potential energy does the diver have?
A cheetah weighing approximately 50 kg was seen chasing a gazelle at a speed of 32.4 m/s. What is the kinetic energy of the cheetah?
PE = mgh
Earth’s
Gravity
P.E. =
(46 kg)
(9.8 m/s2)
(10 m)
= 4,508 J
KE = 1mv2 2
(1)_____________ 2
(50 kg)
(32.4 m/s)2
K.E. =
= 26,244 J

20. Forms of Energy (Grouping Activity)
Organize the 24 laminated sheets into six groups. Each group should consist of:
words representing a form of energy (bold)
some descriptions describing the form of energy (bullet)
a visual representation of the form of energy.
When you think the sheets are correctly grouped, have me come and confirm whether it is correct.
Complete the table.

21. 11/2/15 1) Hand in your vocabulary chart
2) Hand in your Kinetic and Potential energy practice
3) Take out your notebook so we can get reorganized.

22. Warm up 11/2/15
1. What type of energy is the energy stored in food and gasoline?
2. What type of energy do objects in motion have?
3. List 2 examples of energy that you used today.

23. Forms of Energy Mechanical Sound Chemical Thermal Electromagnetic
Nuclear

24. Mechanical Energy energy that moves objects
the total amount of potential and kinetic energy combined.
Example:
-A bouncing ball has both KE and PE. Add the 2 together to find mechanical energy

25. Sound Energy
Caused by the vibration of particles in a solid, liquid, or gas
must have a medium to travel through - cannot travel through empty space
sound in a vacuum
This person is listening to someone telling a secret. How are the sound waves being generated?

26. Chemical Energy
potential energy stored in the chemical composition of matter.
We eat glucose and convert the chemical energy in the bonds to live.
Chemical bonds in gasoline are converted into mechanical energy in our vehicles.
The chemical energy in coal is conveted into thermal and electrical energy. C H O HO OH
≈464,000 J
≈347,000 J
Glucose

27. has more thermal energy? Why?
when particles move faster they have more thermal energy than when they move slower
Which box of particles
has more thermal energy? Why?

28. Electromagnetic Energy
Travels through space in the form of electromagnetic waves
light, electricity, and magnetism are representative of electromagnetic energy
can travel through empty space
Image taken from:

29. Nuclear Energy
is released when an atom’s nucleus breaks apart (fission) or when the nuclei of two atoms come together (fusion)
Example:
Nuclear fission takes place in a nuclear power plant while nuclear fusion takes place in the Sun. + +
Is nuclear fission or nuclear fusion taking place? Explain your reasoning.
Deuterium
Tritium +
helium
neutron
Video on fusion in the sun

30. Identify the Form of Energy
Thermal
(burner increases movement
of H2O molecules)
Mechanical
(moving gears)
Electromagnetic
(radio waves)
Chemical
(food)
Electromagnetic
(electricity)

31. Energy Conversions a change from one form of energy into another
during conversions, some energy is usually lost as heat
Example
Electromagnetic energy (in the form of light) from the Sun is converted, by plants, into chemical energy in the form of glucose
6CO2 + H2O C6H12O6 + 6O2
light energy
Light
Energy
CO2
H2O O2
C6H12O6

32. Nuclear energy Two types:
Fusion occurs when nuclei are smashed together (the sun does this)
video
Fission occurs when nuclei are split apart. Nuclear bombs and power plants do this.

33. Identify the Energy Conversions
2. Electromagnetic Energy
(electricity moving through the wires)
Wires
The apparatus to the right was placed into a bell jar. What energy conversions take place when it is operating?
Battery
Buzzer
1. Chemical energy
(in the battery)
3. Sound Energy
(noise coming from the buzzer)

34. In your Notebook
Describe all of the energy conversions in the following situation:
You turn on a toaster and toast a piece of bread. You lift up and eat the toast. After breakfast, you go for a run.

35. On your white board
On a cold morning you start your car. To melt the ice on the windshield you turn on the heat. Once the ice is clear you drive to school.

36. On a cold day your rub your hands together to warm them up.

37. Law of Conservation of Energy
states that energy can be neither created nor destroyed
the total amount of energy in a closed system is the same
energy can be changed from one form to another, but all of the different forms of energy add up to the same total amount of energy
PE = 24 J
KE = 0 J
PE =
KE =
12 J
12 J
A bird steals a sandwich and drops it from a height of 7 m before eating it. What would be the sandwich’s approximate PE and KE as it falls to the ground if air resistance is negligible?
PE =
KE =
0 J
24 J

38. Efficiency = energy output x 100
Energy Efficiency
comparison of the amount of energy before a conversion with the amount of useful energy after a conversion
the closer the energy (work) output is to the energy (work) input, the more efficient the conversion is
more efficient conversions  less waste
Formula:
Sample Problem
A particular cell phone charger uses joules per second when plugged into an outlet, but only 1.31 joules per second actually goes into the cell phone battery. The remaining joules are lost as heat. That’s why the battery feels warm after it has been charging for a while. How efficient is the charger?
1.31 J
Efficiency = energy output x 100
energy input
= ____ x 100
4.83 J
= 27.1%
Sample Problem taken from:

39. Efficiency practice
If a child on a swing has 900J of Gravitational potential energy at the top of the swing and 700J of Kinetic energy at the bottom of the swing, what was the efficiency of that conversion?
700J x 100 = 77.7%
900J

40. How efficient the conversion of electrical energy to thermal energy in your toaster if the input of electricity is 300J and the output of thermal energy is 250J?
250J x 100= 83.3%
300J

41. Power practice