Summary
Demos and activities in this lesson are intended to illustrate the basic concepts of energy science—work, force, energy, power etc., and the relationships among them. The "lecture" portion of the lesson includes many demonstrations to keep students engaged, yet has high expectations for students to perform energy-related calculations and convert units. A homework assignment and quiz are provided to reinforce and assess these basic engineering science concepts.Engineering Connection
The basic concepts of work, force, energy and power are fundamental physics concepts utilized in many engineering calculations and design. Every engineered device that moves, lifts or pushes requires energy. An engineer must know how to calculate the power and energy needed to do the necessary work or provide the required heat.
Most of the world uses metric units to quantify engineering terms, while the US still performs some of its engineering work using the old British system. Metric units are all based on fundamental physics quantities. That makes the metric Joule, Newton and watt much easier to use and calculate than the British BTU (British thermal unit), horse power, pound force, and slug. In this unit, metric units are used, but a few British units are included as reference point because they are more familiar for many energy measurements.
Learning Objectives
After this lesson, students should be able to:
- Define and contrast energy, work and power.
- Given mass, distance, and time, calculate work, force and power using appropriate units.
- Given the conversion formulas, convert between horsepower and kilowatts.
- Use measurement tools to apply the concepts of work, power and energy to real-life examples.
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Educational Standards
Each TeachEngineering lesson or activity is correlated to one or more K-12 science,
technology, engineering or math (STEM) educational standards.
All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN),
a project of D2L (www.achievementstandards.org).
In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics;
within type by subtype, then by grade, etc.
Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.
All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).
In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.
Next Generation Science Standards: Science
- Construct, use, and present arguments to support the claim that when the kinetic energy of an object changes, energy is transferred to or from the object. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
Common Core State Standards: Math
- Use ratio reasoning to convert measurement units; manipulate and transform units appropriately when multiplying or dividing quantities. (Grade 6) Details... View more aligned curriculum... Do you agree with this alignment?
- Solve real-world and mathematical problems by writing and solving equations of the form x + p = q and px = q for cases in which p, q and x are all nonnegative rational numbers. (Grade 6) Details... View more aligned curriculum... Do you agree with this alignment?
- Fluently divide multi-digit numbers using the standard algorithm. (Grade 6) Details... View more aligned curriculum... Do you agree with this alignment?
- Fluently add, subtract, multiply, and divide multi-digit decimals using the standard algorithm for each operation. (Grade 6) Details... View more aligned curriculum... Do you agree with this alignment?
International Technology and Engineering Educators Association: Technology
- Energy can be used to do work, using many processes. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
- Power is the rate at which energy is converted from one form to another or transferred from one place to another, or the rate at which work is done. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
National Council of Teachers of Mathematics: Math
- solve problems that arise in mathematics and in other contexts (Grades Pre-K - 12) Details... View more aligned curriculum... Do you agree with this alignment?
- recognize and apply mathematics in contexts outside of mathematics (Grades Pre-K - 12) Details... View more aligned curriculum... Do you agree with this alignment?
- use representations to model and interpret physical, social, and mathematical phenomena (Grades Pre-K - 12) Details... View more aligned curriculum... Do you agree with this alignment?
- understand and use ratios and proportions to represent quantitative relationships (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
- understand the meaning and effects of arithmetic operations with fractions, decimals, and integers (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
- use the associative and commutative properties of addition and multiplication and the distributive property of multiplication over addition to simplify computations with integers, fractions, and decimals (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
- relate and compare different forms of representation for a relationship (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
- develop an initial conceptual understanding of different uses of variables (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
- use symbolic algebra to represent situations and to solve problems, especially those that involve linear relationships (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
- model and solve contextual problems using various representations, such as graphs, tables, and equations (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
- understand both metric and customary systems of measurement (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
- understand relationships among units and convert from one unit to another within the same system (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
- select and apply techniques and tools to accurately find length, area, volume, and angle measures to appropriate levels of precision (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
- solve simple problems involving rates and derived measurements for such attributes as velocity and density (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
- use observations about differences between two or more samples to make conjectures about the populations from which the samples were taken (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
National Science Education Standards: Science
- Use appropriate tools and techniques to gather, analyze, and interpret data. The use of tools and techniques, including mathematics, will be guided by the question asked and the investigations students design. The use of computers for the collection, summary, and display of evidence is part of this standard. Students should be able to access, gather, store, retrieve, and organize data, using hardware and software designed for these purposes. (Grades 5 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
- Develop descriptions, explanations, predictions, and models using evidence. Students should base their explanation on what they observed, and as they develop cognitive skills, they should be able to differentiate explanation from description--providing causes for effects and establishing relationships based on evidence and logical argument. This standard requires a subject matter knowledge base so the students can effectively conduct investigations, because developing explanations establishes connections between the content of science and the contexts within which students develop new knowledge. (Grades 5 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
- Think critically and logically to make the relationships between evidence and explanations. Thinking critically about evidence includes deciding what evidence should be used and accounting for anomalous data. Specifically, students should be able to review data from a simple experiment, summarize the data, and form a logical argument about the cause-and-effect relationships in the experiment. Students should begin to state some explanations in terms of the relationship between two or more variables. (Grades 5 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
- Use mathematics in all aspects of scientific inquiry. Mathematics is essential to asking and answering questions about the natural world. Mathematics can be used to ask questions; to gather, organize, and present data; and to structure convincing explanations. (Grades 5 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
- Mathematics is important in all aspects of scientific inquiry. (Grades 5 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
- Energy is a property of many substances and is associated with heat, light, electricity, mechanical motion, sound, nuclei, and the nature of a chemical. Energy is transferred in many ways. (Grades 5 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
New York: Math
- Fluently divide multi-digit numbers using the standard algorithm. (Grade 6) Details... View more aligned curriculum... Do you agree with this alignment?
- Fluently add, subtract, multiply, and divide multi-digit decimals using the standard algorithm for each operation. (Grade 6) Details... View more aligned curriculum... Do you agree with this alignment?
- Solve real-world and mathematical problems by writing and solving equations of the form x + p = q and px = q for cases in which p, q and x are all nonnegative rational numbers. (Grade 6) Details... View more aligned curriculum... Do you agree with this alignment?
- Use ratio reasoning to convert measurement units; manipulate and transform units appropriately when multiplying or dividing quantities. (Grade 6) Details... View more aligned curriculum... Do you agree with this alignment?
Introduction/Motivation
Students will have been introduced to the global energy problem and how their choices impact the energy situation.The purpose of this lesson is to introduce students to the basic concepts of energy and to use that knowledge in an experiment to determine how much a power a human being can provide. To begin stirring thoughts on energy, consider the following questions:
- What do you think about when you hear the term "energy?"
- What do students think about when they hear the term "energy?"
- Where/how do you use energy in your lives? Name a few things that we do that use energy. Can use examples from game.
- What happens when we do not have access to energy (i.g. electric power), such as during summer blackouts or ice storms)?
Engineers and scientists have learned how to "capture" energy to run machines, provide power and heat our homes. The term "capture" is really not appropriate. Thermodynamic principles tell us that energy can neither be created or destroyed, only converted into a different form. Sometime that form helps us do work, while other times it creates heat. Most of the time, energy transformations create both heat and work.
Lesson Background and Concepts for Teachers
Energy is the ability to do work and is used in order to perform work.
Power is the rate at which work is done.
There are mathematical representations of work and power.
There are various units of energy, work and power.
The concepts and definitions of work, energy and power can be illustrated with a few examples:
A force is a push, pull, or twist
- Force = mass X acceleration
- Drop a ball . What is pulling it towards the ground? (Gravity. Acceleration of gravity [9.81 m/s^{2}].)
- Who first formulated scientific understanding of gravity? (Sir Isaac Newton. We name the unit of measure of force after him.)
- 1 Newton (N) = kg *m/s^{2}
- In the metric system, if you can remember the equation (F=m•a) then you can remember the corresponding units (or vice versa).
Energy is the ability to do work.
- Work is a force acting over a distance to move an object.
- Work = force X distance
- Metric units are measured in Joules (J=N•m)
- Reinforce the concept of work with the Student Push/Pull Demo
- Ask for two volunteers.
- Have one push against the wall and one push on a chair so that the chair moves at least 0.5 meters.
Discuss as a class:
- Did either one or both of these students do any work? The one pushing on the chair did work; the other did not. "Work" requires that an object be moved.
- Did either of these expend energy? Yes – energy contributes to doing work, but not all energy successfully does work. (Heat was generated by the student who did not do work.)
Introduce Newton's second law to have students apply their knowledge of forces, work, and energy:
- Energy transfer is described with Newton's first law. An object in motion will remain in motion unless acted on by another force.
- What happens to the energy of an object when its motion changes?
Show Newton's second law with the following example / demonstration:
Scenario 1:
- Consider a hockey puck is pushed on a table surface. Once in motion will the hockey puck remain in motion? (Students: No, the puck will stop.) Demonstrate by pushing a hockey puck, or other object, across a table.
- Well, I thought that Newton's law tells us that an object will remain in motion unless acted upon by another force. Is there another force acting on the object? (Let students respond.)
- Yes, friction is the force acting on the hockey puck, causing its motion to stop. Energy was applied to the puck via the initial push, and the friction force opposed the puck's motion causing it to stop. What happened to the energy that the puck had? (Let students respond.)
- The energy was transferred to the table (or lost) in the form of heat.
Scenario 2:
- Imagine the hockey puck is pushed on an air hockey table, or on ice. Will the puck remain in motion? (Let students respond. Students: Yes!) If possible, demonstrate with a mini air hockey table, or freeze water in an aluminum pie pan.
- Teacher: Why does it remain in motion? What happened to the friction? (Let students respond.)
- The air coming up from the table reduces the amount of friction between the table and the puck, so once a force is applied to the puck it will maintain its energy.
- What happens if another force acts on the object, like a hit to the puck from an air hockey player? (Let students respond.)
- The motion of the puck changes, because energy was added to the puck from the hit.
Power is how fast work is done (or the rate at which work is done).
- Power = work/time OR Power = energy used/time
- Power is now measured in units of watts after James Watt. Mr. Watt built the first steam engine. When he was selling it, he advertised to farmers and miners that it could give more power than a horse. He said that it had 1.5 horsepower. Although the unit of horsepower is still used today, it does not accurately describe how many horses it replaces because not every horse is the same.
- A watt is defined based on the equation W=J/s
Here are a few examples:
- Jim's daughter locked herself in the bathroom and his wife is on her way home and sure to be angry. If Jim throws himself against the door with a force of 200 N opening the door 0.5 m in 2 seconds. What is his Work and Power? (Answers: W= (200 N)(0.5 m)=100 J, P=(100J)/(2s) = 50 W)
- A crane lifts a car that weighs 2000 kg a distance of 5m in 2min (convert minutes to seconds with the class: 120s). What is the Force (g=9.8m/s^{2}), Work and Power? (Answers: F=19600 N, W= 98000 J, P= 817 W or .082 kW)
Vocabulary/Definitions
Btu: The amount of energy needed to raise 1 lb of water 1 degree Fahrenheit (1 Btu ~ heat energy from one wooden match); 1 Btu = 1055 Joules
energy: The ability to do work; =power x time; Joule (J)
force: A force is a push, pull, or twist; F = mass X acceleration, Newton (N) =kg/m/s^2
horsepower: Unit for measuring mechanical or electrical power; 1 hp = 746 watts
joule: The SI (standard international) unit for energy and work. J = W•s = N•m
kilogram: The SI unit for mass; kg
kilowatt: Typical unit for electrical power; 1 hp = 746 watts
kilowatt hour: Typical unit for electrical energy; kWh
meter: The SI unit for distance; m
power: The rate at which work is done; = work / time (or =energy/time); Watt = J/s
work: A force acting over a distance to move an object; = force x distance; Joule (J)
Associated Activities
- Human Power - Students do work by lifting a known mass over a period of time. Then they calculate force, work, energy and power in metric units.
Lesson Closure
First Day
- Give out energy basics homework.
- Reinforce energy, work and power.
- Ask the students: What did we learn today? Can anyone define work, power, energy?
Attachments
Assessment
Post-Introduction Assessment: Assign students the attached Homework Handout, in which they complete word problems that require calculations of force, work, energy and power.
Lesson Summary Assessment: A quiz at the end of the lesson requires students to apply knowledge to specific calculations of force, work and power, and apply some of these scientific fundamentals to the unit project.
Other Related Information
This lesson was originally published by the Clarkson University K-12 Project Based Learning Partnership Program and may be accessed at http://www.clarkson.edu/highschool/k12/project/energysystems.html.
Contributors
Susan Powers; Jan DeWaters; and a number of Clarkson and St. Lawrence students in the K-12 Project Based Learning Partnership ProgramCopyright
© 2013 by Regents of the University of Colorado; original © 2008 Clarkson UniversitySupporting Program
Office of Educational Partnerships, Clarkson University, Potsdam, NYAcknowledgements
This lesson was developed under National Science Foundation grants no. DUE 0428127 and DGE 0338216. However, these contents do not necessarily represent the policies of the National Science Foundation, and you should not assume endorsement by the federal government.
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