## Getting the Advantage: Simple Machines

Getting the Advantage: Simple Machines Forces & Motion 6 Introduction Overview Students explore the meaning of tools and machines, and discover how...
Author: Gary Warner

Forces & Motion

6

Introduction Overview Students explore the meaning of tools and machines, and discover how work is changed or made easier. They take a look at two kinds of simple machines, inclined planes and levers. Student groups investigate and compare the construction and function of the various simple machines that are included in these two groups. ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○

Big Idea: Simple machines make work easier by changing how the work is done. ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○

Purpose

Materials and Preparation

For Students to Do

Kit Materials

1. Think about and discuss tools and the purpose of tools. 2. Investigate inclined planes and levers.

For Students to Know 1. Everyday tools are simple machines. 2. Simple machines change the effort required to do work or increase the speed of the work done. 3. There are two major categories of simple machines, inclined planes and levers. 4. A lever system has four parts: the arm, the load (object to be moved), the fulcrum (the pivot point), and the effort (applied force). 5. The location of the fulcrum in a lever system determines the class of the lever.

TEAMS Science—Forces & Motion © 2001-2002 by the Los Angeles County Office of Education

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washers spring scales wooden fulcrums

Teacher Provided Materials • • • • • •

inclined plane tools (see suggestions below) cm rulers tape clay second and third class lever examples (see suggestions below) string

Duplication •

Student Activity Sheets, pages 6:5, 6:8, 6:11, 6:12

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Advance Preparation Review viewing activity descriptions in detail. Collect and organize materials as described below. Try the activities yourself! Viewing Activity #1 Gather common inclined plane tools, and examples of inclined planes. Some examples: carpentry nails, plastic knives or forks, doorstops, tent stakes, various ramps and screws. Viewing Activity #2 Have student groups make a ball of clay (2 cm in diameter) and tape 4 washers together with masking tape. Viewing Activity #3 Collect examples of second and third class levers (objects and/or pictures). Some second class lever examples: wheelbarrow, crowbar, bottle opener, doors. Some third class lever examples: broom, shovel, fly swatter, spoon, tennis racket, baseball bat.

Literature Connection •

Lampton, Christopher. Bathtubs, Slides, Rollercoaster Rails: Simple Machines That Are Really Inclined Planes. Millbrook, 1991. Lampton, Christopher. Seesaws, Nutcrackers, Brooms: Simple Machines That Are Really Levers. Millbrook, 1991.

TEAMS Science—Forces & Motion © 2001-2002 by the Los Angeles County Office of Education

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Forces & Motion

Getting the Advantage: Simple Machines Outline

6 Notes

Viewing Activities: “Let’s Do Science!” Hands-On: Plain & Simple Machines Students think about and share their ideas about tools. They consider the relationships among force, work and machines, and investigate inclined plane tools to find out how work can be made easier. In the classroom, students discuss findings. (Viewing Activity #1, page 6:4)

Hands-On: A First Class Act Students continue to explore simple machines as they begin their investigation of levers. Using a ruler, clay, washers, and a wooden fulcrum, they construct and investigate a lever system. Students observe and discuss findings in the classroom. (Viewing Activity #2, page 6:6)

Hands-On: In A Class of Their Own Students take a closer look at the second and third class levers. They compare actual examples of these levers with each other and with examples of the first class lever. The arrangement of components and use of the second and third class lever are explored. Students share their ideas and discuss results in the classroom. (Viewing Activity #3, page 6:9)

Post-Viewing Activity Hands-On: In A Class of Their Own Students continue to explore 2nd and 3rd class levers as they take a look at some tools that are based on these lever classes. Students identify and discuss the components of the tools. They compare the tools in construction and use. (Post-Viewing Activity, page 6:13)

Hands-on Materials Caution: Do not try this at home!

TEAMS Science—Forces & Motion © 2001-2002 by the Los Angeles County Office of Education

Transparency

Activity Sheet

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Viewing Activity #1 Hands-On: Plain & Simple Machines Description

of inclined plane tools. (How are the tools Students explore the various types of inclined similar?) planes. They take a look at how this simple ma- 4. Record and discuss ideas and conclusions. chine can be used. Students collaborate to find solutions to problems related to the force, work, Teacher 2 Teacher Machines are devices that help make better use of and inclined planes. forces. A machine, which can change the force Materials required to do work, can be very complex, like a per student group source car, or very simple, like a toothpick. 1 inclined plane tool classroom Simple machines are the basis of the tools that per student we use everyday to help us do many things. There – activity sheets page 6:5 are two general categories of simple machines: inclined planes and levers. Leading the Activity The inclined plane lifts, splits or cuts objects. A The studio teacher introduces and leads the activramp, for example, is an inclined plane. Moving ity. Shows students a variety of tools and invites an object along a ramp uses less force than is them to think about “tools.” Makes the connection required to lift the object vertically to that height. between force (push, pull), work (pushing, pullA screw is an inclined plane wrapped around a ing of objects), and machines. Takes students on a cylinder or a cone. The wedge is formed by two video field trip to explore inclined planes. Encourinclined planes placed back to back, making one ages student groups to investigate their examples end wide and the other end very narrow. The edge of inclined planes to find out how work is made of the wheel on a pizza cutter is a good example of easier. Involves students in discussion of observaa basic wedge. tions and ideas about these inclined planes. Challenges students to consider the application of force and how it affects the amount of work done. The classroom teacher facilitates the activity. Asks guiding questions throughout the investigaram books p tion. Involves students in a discussion to share the various inclined tools, the uses, and the similarities.

inclined plane

Procedure 1. Observe the inclined plane tool. 2. Discuss how the tool is constructed, and what it does. (Where is the force applied? How does it help to do the work? How is the work made easier? ) 3. Discuss comparisons of the various examples

screw TEAMS Science—Forces & Motion © 2001-2002 by the Los Angeles County Office of Education

wedge Program 6:4

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Student Activity Sheet Viewing Activity #1: Plain & Simple Machines A. Observe and discuss the inclined plane tool. 1. What is the purpose of the tool? _______________________________________________________ ______________________________________________________________________________________ 2. Where is the force applied? ____________________________________________________________ ______________________________________________________________________________________ 3. How would you do the work without the tool? __________________________________________ ______________________________________________________________________________________ 4. How does the tool change the work or make it easier? ____________________________________ ______________________________________________________________________________________

B. Draw a picture of the tool. Indicate where the force is applied.

Inclined Plane Tool

Which type of inclined plane does this tool use? Wedge, Ramp, Screw? _______________________ TEAMS Science—Forces & Motion © 2001-2002 by the Los Angeles County Office of Education

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Viewing Activity #2 Hands-On: A First Class Act Description Students take a look at the second category, levers. They explore the first of three classes of levers, where the pivot point is between the applied force and the load. Students investigate how this machine functions, the work that results, and the advantages of use.

Materials per student group 1 cm ruler – masking tape 4 washers 1 ball of clay (2 cm diameter) 1 wooden fulcrum per student – activity sheet

source classroom classroom kit classroom kit page 6:8

Leading the Activity The studio teacher introduces and describes the activity. Challenges students to come up with ideas about which placement of a brick (the fulcrum) under a four foot board will be best to lift a heavy load on one end, while pushing down on the other. Demonstrates how students can make a model to investigate the problem and challenges them to find solutions. Encourages students to discuss and share ideas and conclusions. Discusses other first class levers we use everyday. Invites students to continue to explore first class levers. The classroom teacher facilitates the activity and asks questions to guide student thinking. Involves students in discussion of ideas, results and conclusions.

Procedure 1. Place the ruler on the wooden fulcrum at the point where the ruler is balanced. 2. Record that point on the activity sheet. 3. Place the clay ball securely at the 30 cm end TEAMS Science—Forces & Motion © 2001-2002 by the Los Angeles County Office of Education

4. 5. 6. 7. 8.

of the ruler. (Keep the clay ball in place through all the trials.) Tape the taped washers on the other end. Record observations. Follow the directions to place the ruler on the wooden fulcrum at 3 other points. Record and discuss observations. Discuss ideas and conclusions.

Teacher 2 Teacher Levers are simple machines that make work easier by helping to lift loads with less effort through transferring the force required to do the work. A lever is a bar or board that pivots around the fulcrum, a point of support. There are three different classes of lever , first, second and third. Each of these levers has the same four components: an arm (the bar or beam), a fulcrum (the pivot point), a load (the object to be moved), and an effort (the applied force needed to move the load). The arrangement of the components, however, differs with each class. The effort, or force, needed to use a lever changes as the length of the arm is changed. In the first class lever, the fulcrum is in between the effort and load. An example of a first class lever is the playground seesaw. The second class lever has the load positioned on the arm between the fulcrum and the effort. An example of a second

1st class

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Fulcrum

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3rd class

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class lever is a wheelbarrow. A third class lever has the effort positioned on the arm between the fulcrum and the load. A spoon and a baseball bat are examples of third class levers. Each of these lever classes also include some tools which use two of the levers put together. Scissors, for example, are an example of a double first class lever. A nutcracker is an example of a double second class lever; and ice tongs, tweezers, or forceps, are examples of a double third class lever.

D ou Ex Lev ble am er pl es

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1st Class Lever

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2nd Class Lever

TEAMS Science—Forces & Motion © 2001-2002 by the Los Angeles County Office of Education

3rd Class Lever

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Student Activity Sheet Viewing Activity #2: A First Class Act 1. Place the wooden fulcrum under this balanced ruler.

0 cm

30 cm

2. Place the clay ball at the 30 cm of your balanced ruler. (Tape the washers on the other end of the ruler. Record your observations. ______________________________________________________ ______________________________________________________________________________________ 3. Where should the fulcrum be placed to balance the clay ball and the washes. Record your idea. Try it and record your observations. _______________________________________________________ ______________________________________________________________________________________ 3. Keep the clay ball and the washers in place for all the trials. Move the wooden fulcrum to the locations indicated on the chart. Record your observations.

Placement of the Fulcrum

Trial 1

21 cm

2

14 cm

3

7 cm

Observations

cm

Your Conclusion Write a statement to explain how changing the position of the fulcrum affects the effort needed to lift and balance a load. _____________________________________________________________________ ______________________________________________________________________________________

TEAMS Science—Forces & Motion © 2001-2002 by the Los Angeles County Office of Education

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Viewing Activity #3 Hands-On: In A Class of Their Own Description Students explore second and third class levers. They continue to explore the major components of the levers: the arm, the pivot point (fulcrum), the applied force (effort), and the load, and how they are arranged. Students compare these levers with each other and the first class lever.

Materials per student group – cm ruler – wooden fulcrum 4 washers (taped) 1 spring scale per student – activity sheet

source classroom kit kit kit page 6:11; 6:12

Leading the Activity The studio teacher introduces and describes the activity. Challenges students to compare examples of how a crowbar and a broom are used. Where are the fulcrum, effort and load in each example? Demonstrates the construction of the second and third class levers. Invites students to construct and investigate second and third class levers. Encourages students to discuss and share ideas, comparisons, and conclusions. The classroom teacher facilitates the activity, asks guiding questions, and encourages investigations and comparisons. Involves students in discussion of ideas, results and conclusions.

4. Place the wooden fulcrum under the 1 cm mark. 5. Attach the spring scale to the string. 6. Use the spring scale to measure the effort it takes to lift the washers. 7. Record and discuss results. 8. Discuss ideas: How does it work? Where is the fulcrum, the effort and the load when this lever is used? 9. Record and discuss ideas. 10. Construct the third class lever model. 11. Tie a piece of string around the center of the ruler (15 cm mark). 12. Place the taped washers (load) at the 30 cm mark. 13. Repeat steps 4–9 for the third class lever model. 14. Compare the second and third class levers. 15. Discuss and record your conclusions.

Procedure 1. Construct the second class lever model. 2. Tie a piece of string around the 30 cm mark of the ruler. 3. Place the taped washers (load) on the ruler at 15 cm.

TEAMS Science—Forces & Motion © 2001-2002 by the Los Angeles County Office of Education

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Getting Ready for Next Time: Where can you find two or more simple machines working together? What simple machines are used? (Hint: Take a look at the classroom pencil sharpener or a bicycle. )

Lever Screw Gear

Wheel & Axle

TEAMS Science—Forces & Motion © 2001-2002 by the Los Angeles County Office of Education

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Student Activity Sheet Viewing Activity #3: In A Class of Their Own 1. Construct the second class lever model. How much effort will it take to lift the washers with the second class lever model? Predict and test. Prediction

Trial 1

Trial 2

Trial 3

Average

2. Construct the third class lever model. How much effort will it take to lift the washers with the third class lever model? Predict and test. Prediction

Trial 1

Trial 2

Trial 3

Average

3. Compare Results How does the effort required to lift the washers with the second class lever compare with the effort needed by the third class lever? ______________________________________________________________________________________ ______________________________________________________________________________________ Where are the load, effort, and fulcrum in the second and third class levers? ___________________ ______________________________________________________________________________________ ______________________________________________________________________________________ ______________________________________________________________________________________

TEAMS Science—Forces & Motion © 2001-2002 by the Los Angeles County Office of Education

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4. Your Conclusions Which type of lever would be best to move a very large, heavy rock? Explain why you think so? ______________________________________________________________________________________ ______________________________________________________________________________________ ______________________________________________________________________________________

Going Further Take a closer look at some 2nd class and 3rd class lever tools. Identify the arm, fulcrum, effort, and load components.

TEAMS Science—Forces & Motion © 2001-2002 by the Los Angeles County Office of Education

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Post-Viewing Activity Hands-On: In A Class of Their Own Description Students continue to explore 2nd and 3rd class levers as they take a look at some tools that are based on these lever classes. Students identify and discuss the components of the tools. They compare the tools in construction and use.

Materials per student group 1 second class lever example 1 third class lever example per student – activity sheet

source classroom classroom page 6:14

Leading the Activity Review with students the components of a lever system and how these components are arranged in the second and third class levers. Invite student groups to investigate the tools based on the second and third class levers. Challenge them to find out how these two classes are different.

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2nd class

Procedure 1. Observe and discuss the second class lever tool. 2. Describe how this tool is used. How would you do the work without the tool? How does it make work easier? 3. Draw a picture of the tool and label the parts. (arm, fulcrum, effort and load) 4. Observe the third class lever tool. 5. Describe how this tool is used. How would you do the work without the tool? How does it make work easier? 6. Draw a picture of the tool and label the parts. 7. Compare the two tools. What are the differences in these two lever classes?

E F

TEAMS Science—Forces & Motion © 2001-2002 by the Los Angeles County Office of Education

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Student Activity Sheet Post-Viewing Activity: In A Class of Their Own 1. Describe how the second class lever tool example works. In the box below, draw a picture of the tool being used. Label the load, effort, and fulcrum.

2. Describe how the third class tool example works. In the box below draw a picture of this tool being used. Label the load, effort, and fulcrum.

TEAMS Science—Forces & Motion © 2001-2002 by the Los Angeles County Office of Education

Program 6:14