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Energy
What Is Energy?
Forms of Energy
Energy Transformations and Conservation
Energy and Fossil Fuels
Table of Contents
Energy
Learning Objectives
1. Describe how energy relates to work and power.
2. Describe kinetic energy and potential energy for various real world examples.
Energy
Energy from Your Food (Calorimetry Lab)Goal- Determine the amount of energy contained in a piece of food (a marshmallow).
Procedure: 1. Fill the soda can with 20 mL of water. 2. Measure the initial temperature of the water & the initial mass of the marshmallow (place the
pie plate, marshmallow, paper clip, and clay on the balance), then the Mr. Nye will light the marshmallow about 1 inch underneath the soda can (held in place by you using tongs).
3. After the marshmallow is JUST finished burning, measure the final temperature of the water.4. Then measure the final mass of the marshmallow. Again, place the pie plate, marshmallow,
paper clip, and clay on the balance to get the final mass of the marshmallow.5. Determine the temperature change (final – initial) and the mass change (initial – final)
[both should be positive].
Data Analysis: Calculate the number of Calories per gram of marshmallow:
cal/g = (20 g Water x 1 cal/g*oC x Temperature change)/Change in mass
1000 calories = 1 Food CalorieFood Calories per gram = (previous calculation)/1000
Theoretical Yield = 3.21 Food Calories/g
*Theoretical yield taken from the nutrition label (100 Food Cal/30 g).*
Energy
Calorimetry Lab ConclusionsAnswer in the complete sentences…
1. How did your actual yield compare to the theoretical yield of 3.21 Food Cal/gram3.21 Food Cal/gram?
2. What are some sources of error in this experiment that would cause the actual yield to be considerably lessconsiderably less than the theoretical yield? Hints: Does all of the heat from the burning marshmallow go directly into the water? If not, then where does most of it go?
3. Keeping in mind that the grill lighter just got the burning started, where did the energy originally comeoriginally come from? How does this experiment demonstrate the reason as to why we need to eat food?
Energy
Learning Objectives
1. Describe how energy relates to work and power.
2. Describe kinetic energy and potential energy for various real world examples.
Energy
Introduction to Kinetic & Potential EnergyPotential Energy is stored energy.
ExamplesExamples: (Chemical) energy stored in a battery or food, a stretched rubber band (Elastic), or a person or an object at a high height (Gravitational)
Kinetic Energy is the energy of movement or motion.
ExamplesExamples: Any object or person that is moving has a certain amount of kinetic energy, Particles that make up matter are constantly moving.
Energy
Kinetic vs. Potential Energy Experiment
Goal: Determine the variables that affect the KE and PE for the go-car as it goes down the ramp for 2 different masses.
Hypothesis: Predict how velocity will affect KE and how the height above the ground will affect PE.
Background:
m = mass, v = velocity, g = acceleration due to gravity, h = height above the ground
Kinetic Energy (KE) = Energy of motion = 1/2mv2
Gravitational Potential Energy (PE) = Stored energy = mgh
Energy
Machine Setup
Mass
m (kg)
Velocity
v
(m/s)
KE
1/2mvv22
(J)
Mass
m
(kg)
Gravity
g
(m/s/s)
Height
h
(m)
PE
mgh
(J)
Top of Ramp & no weights
0.25 0 0.25 9.8 0.5
Top of Ramp & weights
0.50 0 0.50 9.8 0.5
Bottom of Ramp & no weights
0.25 From your data
0.25 9.8 0
Bottom of Ramp & weights
0.50 From your data
0.50 9.8 0
Energy
Conclusions (in complete sentences)1. State the relationships between the following
variables (use the equations for help too):
a) Velocity and KE
b) Height above the ground and Gravitational PE
2. Where on the ramp would the KE & PE be about equal? Explain your answer with evidence from the experiment. Hint- Where was there 0 KE but plenty of PE and 0 PE but plenty of KE?
3. So, was any energy lost (outside of friction and human error), or was the energy transformed from one form to another (such as KE to PE or PE to KE)? How was the energy transformed as the go-car went down the ramp?
Energy
Learning Objective
1. Describe kinetic energy and potential energy for various real world examples.
Energy - What Is Energy?
Kinetic Energy
Kinetic energy increases as mass and velocity increases.
Energy - What Is Energy?
Potential Energy
Gravitational potential energy increases as weight and height increase.
Energy - Energy Transformations and Conservation
Energy Transformations
Most forms of energy can be transformed into other forms.
Energy - Energy Transformations and Conservation
Transformations BetweenPotential and Kinetic Energy
A pendulum continuously transforms energy from kinetic to potential energy and back.
Energy
What’s the difference between kinetic and potential energy?
A. Kinetic energy is stored energy while potential energy is the energy of motion.
B. Kinetic energy deals with movement while potential energy is stored energy.
C. They are the same type of energy (just different names).
D. I don’t know because I am not living up to my fullest potential.
Energy
Which of the following would have the most kinetic energy?
A. A person standing still on the ground.
B. A person standing on a cliff.
C. A bowling ball rolling at 2 m/s.
D. A ping pong ball bouncing at 2 m/s.
Energy
What happens to a car’s kinetic energy as it decelerates to a stop at a red light?
A. The KE remains the same.
B. The KE increases.
C. The KE decreases.
D. The KE increases, then decreases.
Energy
Where on the diagram below would the ball have the most kinetic energy?
A. Point A
B. Point B
C. Point C
D. None of the above
A
B
C
Energy
Which of the following describes what happens to a basketball’s potential and kinetic energy as it falls down through the basketball hoop to the ground?
A. The KE decreases while the PE increases.
B. The KE increases while the PE decreases.
C. The KE and PE both increase together.
D. The KE and PE both decrease together.
Energy
In which scenario would the skier have the most potential energy?
A. A small skier at the top of a mountain.
B. A small skier at the bottom of a mountain.
C. A large skier at the top of a mountain.
D. A large skier at the bottom of a mountain
Energy
Which of the following best explains what happens to potential energy and kinetic energy as a skier
goes down a mountain?
A. Kinetic energy is transformed into potential energy as the skier goes down the mountain.
B. Potential energy is transformed into kinetic energy as the skier goes down the mountain.
C. Potential energy and kinetic energy both increase as the skier goes down the mountain.
D. Kinetic and potential energy remain the same.
Energy
Practice Test Answers1- The person who passed you is your reference point, so you’ll feel like you’re going slower.
2- velocity (speed and direction)
3- Walking then jogging & sled riding down a hill
4- Motion
5- Air resistance slows objects down in free fall.
6- Friction
7- Gravity causes objects to accelerate at 9.8 m/s/s towards the Earth.
8- House: greatest mass
9- Moving a golf ball at 2 m/s/s
Energy
Practice Test Answers10- Car at 20 mph
11- lowering the applied force
12- Greater than 1
13- Wedge
14- lower than the output force or load weight
15- The smaller applied force is over a larger distance than the larger output force (which is over a shorter distance)
16- Scissors, bike, car, human body, etc.
17- Slow the object down and/or lower its mass
18- Potential energy increases as kinetic decreases (as the snowball goes up higher); then the Potential energy decreases as kinetic energy increases (as the snowball goes down and increases in speed).
Energy
Practice Test Answers19- Increase the distance (spread the objects farther apart) or lower the mass.
20- Straight slanted line going up and to the right or down and to the right.
21- Straight horizontal line going across
22- Find the slope (rise/run = change in distance/change in time)
23- Straight horizontal line; slanted line going down and to the right.
24- 1st and 2nd class levers lower the applied force; 1st class changes the direction of the force too.
25- scissors, pliers, see-saw, crowbar
26- Wheelbarrow, bottle opener, door
Energy
Practice Test Answers27- The applied force should be pointing up the ramp.
28- increase (M.A. = output force/input force)
29- Moving fast and trying to stop but end up still moving forward; trying to move a heavy object from rest and it doesn’t move easily.
30- Rocket taking off- Fuel burns (downward force) which causes the opposite reaction of the rocket moving upward; punching a wall- hit a wall and the wall pushes back (possibly causing injury)
Energy
What You Know
What You Learned
Using Prior KnowledgeBefore you read, look at the section headings and visuals to see what this section is about. Then write what you know about energy in a graphic organizer like the one below. As you read, write what you learn.
1. The joule is the unit of work.2. Energy has different forms.
1. Power is the rate at which energy is transferred.2. The two basic kinds of energy are potential energy and kinetic
energy.
- What Is Energy?
Energy
Links on Energy
Click the SciLinks button for links on energy.
- What Is Energy?
Energy
End of Section:What Is Energy?
Energy
Calculating Mechanical Energy
The kinetic energy of a 500-N diver during a dive from a 10-m platform was measured. These data are shown in the graph.
- Forms of Energy
Energy
Calculating Mechanical Energy
About 1000 J
Reading Graphs:
According to the graph, how much kinetic energy does the diver have at 8 m?
- Forms of Energy
Energy
Calculating Mechanical Energy
Kinetic energy = about 2000 J; potential energy = about 3000 J
Calculating:
Using the graph, find the kinetic energy of the diver at 6 m. Then calculate the diver’s potential energy at that point.
- Forms of Energy
Energy
Calculating Mechanical Energy
About 5000 J
Inferring:
The mechanical energy of the diver is the same at every height. What is the mechanical energy of the diver?
- Forms of Energy
Energy
Building VocabularyAfter you read the section, reread the paragraphs that contain definitions of Key Terms. Use the information you have learned to write a definition of each Key Term in your own words.
- Forms of Energy
Key Terms: Examples:
mechanical energy The form of energy associated with the position and motion of an object is called mechanical energy.
thermal energy The total potential and kinetic energy of the particles in an object is called thermal energy.
electrical energy The energy of electric charges is electrical energy.
chemical energy Chemical energy is potential energy stored in the chemical bonds that hold chemical compounds together.
Key Terms: Examples:
nuclear energy
electromagnetic energy
A type of potential energy called nuclear energy is stored in the nucleus of an atom.
The sunlight that you see each day is a form of electromagnetic energy.
Energy
Links on Forms of Energy
Click the SciLinks button for links on forms of energy.
- Forms of Energy
Energy
End of Section:Forms of Energy
Energy - Energy Transformations and Conservation
Energy Transformations
Most forms of energy can be transformed into other forms.
Energy - Energy Transformations and Conservation
Transformations BetweenPotential and Kinetic Energy
A pendulum continuously transforms energy from kinetic to potential energy and back.
Energy
Physics-Related Jobs
Job Title Description Salary
Architect Design buildings and other structures Average $104,000
Nuclear Physicist
Work with nuclear reactors to provide clean energy
$112,000-143,000
Forensic Scientist
CSI lab work (such as shot tracking) $49,000-62,000
Radiation Technician
Produce medical scans (such as X-Rays, CT scans, MRI’s, & sonograms)
Average $58,000
Research & Development
Studies to help the world through Military Design (Weapons, Armor, Aircraft), Geophysics (Gas Drilling), Optical physics, Space physics, etc.
$62,000-110,000 (but can vary)
Energy
Introduction to ChemistryHindenburg-Hydrogen Gas Explosion
Safety Protocol:1. Do NOT touch anything on the back table until instructed to
do so.2. Follow Lab Directions (if you are unsure, then ask).3. Notify teacher of spills, broken or breaking glassware, and any
other problems.
Energy
Energy Transformations Activity
Click the Active Art button to open a browser window and access Active Art about energy transformations.
- Energy Transformations and Conservation
Energy
Question Answer
Asking QuestionsBefore you read, preview the red headings. In a graphic organizer like the one below, ask a question for each heading. As you read, write answers to your questions.
What is an energy transformation?
An energy transformation is a change from one form of energy to another.
What are some examples of transformations between potential and kinetic energy?
Juggling and pendulums show transformations between potential and kinetic energy.
What is conservation of energy?
The law of conservation of energy states that energy cannot be created or destroyed.
- Energy Transformations and Conservation
Energy
End of Section:Energy
Transformations and Conservation
Energy - Energy and Fossil Fuels
Use of Fossil Fuels
Fossil fuels can be burned to release the chemical energy stored millions of years ago.
Energy
Previewing VisualsWhen you preview, you look ahead at the material to be read. Preview Figure 18. Then write two questions that you have about the diagram in a graphic organizer like the one below. As you read, answer your questions.
Using Fossil Fuel Energy
Q. What energy transformation occurs in the sun?
A. Nuclear energy to thermal energy and electromagnetic energy
Q. What energy transformation takes place when coal is burned?
A. Chemical energy to thermal energy
- Energy and Fossil Fuels
Energy
Links on Energy Transformations
Click the SciLinks button for links on energy transformations.
- Energy and Fossil Fuels
Energy
Use of Fossil Fuels
Click the Video button to watch a movie aboutthe use of fossil fuels.
- Energy and Fossil Fuels
Energy
End of Section:Energy and Fossil Fuels
Energy
exists as measured inis the ability
to do
can bewhich at a
given rate is
Graphic Organizer
Kinetic energy
Energy
Potential energy
Elastic
WorkJoules
Gravitational Power
Energy
End of Section:Graphic Organizer
