Lever
Design and Engineering An Introduction to Simple Machines Educational Objectives
After this lesson, students should be able to understand and apply the following concepts: Basic elements of a lever Differentiate between first, second, and third class levers Calculate mechanical advantage Construct a first, second, and third class lever Conduct an authentic assessment of mathematical predictions and calculations Intrinsic value of levers and the ability to apply that knowledge to future applications and solutions
Education Standards Next Generation Science Standards
Common Core Standards
Standards for Technological Literacy
3-5-ETS1-1 3-5-ETS1-2 3-5-ETS1-3
W.5.7 W.5.9 MP.2 MP.4
2.K-2 2.3-5 2.6-8 2.9-12 8.K-2 8.3-5 8.6-8 8.9-12 9.K-2 9.3-5 9.6-8 9.9-12 10.K-2 10.3-5 10.6-8 10.9-12
MS-ETS1-1 MS-ETS1-2 MS-ETS1-3 MS-ETS1-4
HS-ETS1-1 HS-ETS1-2 HS-ETS1-3 HS-ETS1-4
RST.6-8.1 RST.6-8.7 RST.11-12.8 MP.5
WHST.6-8.9 RST.11-12.7 RST.11-12.9 SL.8.5
Welcome Activity Information
This design and engineering project is designed to introduce students to one of the six simple machines, the lever. Students will learn how a lever works by building one, applying the mathematics behind it, as well as learning key terms related to the subject matter.
Classroom Management
This activity packet should serve as a guide for teachers and students to learn about important concepts in design and engineering. Students can work in groups of up to four throughout this activity.
Resources
Each group of four students should use one Rokenbok SnapStack Module or one Rokenbok Advanced Projects Lab.
Activity Time 120-180 Minutes
Table of Contents Simple Machines: Lever
Information
Objectives ........................................................................................................... Standards .......................................................................................................... Activity Information ............................................................................................. Classroom Management ..................................................................................... Resources ........................................................................................................... Activity Time ........................................................................................................ Getting Started ................................................................................................... Building Basics ...................................................................................................
Lever
Levers ................................................................................................................ Science Concepts................................................................................................ Technology and Engineering ................................................................................ Build Plan: Levers ............................................................................................... Math Concepts ................................................................................................... Design Challenge: Catapult .................................................................................. Design Process ................................................................................................... Design Reflection ................................................................................................. Presentation ........................................................................................................ Assessment .........................................................................................................
1 1 2 2 2 2 3 4 5 6 7 8-16 17 18 19-20 21 22 23
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Getting Started Introduction
In order to be prepared to learn about the lever, the following key terms have been provided below. These terms will be frequently used throughout the lesson. A bank of online key search terms have also been provided. Use a computer to research these terms as you progress through the lesson.
Key Terms Lever:
A rigid bar resting on a pivot, used to help move a heavy or firmly fixed load with one end when pressure is applied to the other.
Simple Machine:
A device that transmits or modifies force or motion.
Effort:
Force used to move an object over a distance.
Resistance/Mass:
Force to overcome, object to be moved, otherwise known as load.
Fulcrum:
The pivot point of a lever that helps create mechanical advantage.
Mechanical Advantage: Advantage gained by use of mechanism in transmitting force.
Online Key Search Terms
Simple Machines Mechanical Advantage Third Class Lever Leverage First Class Lever Prybar Linkage Second Class Lever Claw Hammer
Resources
The Rokenbok SnapStack Module or Advanced Projects Lab can be used to complete the remainder of this lesson.
SnapStack Module
Advanced Projects Lab 3
Building Basics Building Basics with Rokenbok
The following tips will be helpful when using the Rokenbok Student Design and Engineering System. Connecting/Separating ROK Blocks: ROK Blocks use a friction-fit, pyramid and opening system to connect. Simply press pyramids into openings to connect. To separate blocks, pull apart. Connecting/Separating Rokenbok Components Smaller Rokenbok components use a tab and opening system to connect. Angle one tab into the opening, and then snap into place. To separate, insert key into the engineered slot and twist. Snapping Across Openings The tabs on Rokenbok components can also be snapped across openings to provide structural support to a design. This will also allow certain designs to function correctly.
Attaching String: In some instances, string may be needed in a design. Lay string across opening. Snap any Rokenbok component with tabs or pyramids into opening. Make sure tabs run perpendicular to string for a tight hold. Measuring: The outside dimensions of each Rokenbok connector block is 2cm3. This means the length, depth, and height are all the same. To determine the size of a Rokenbok build in cm, simply count the number of openings and multiply by two. Repeat this process for length, depth and height.
2cm 9 Openings 2cm 18cm
2cm
3 Openings
6cm
4
Levers What is a Lever?
A lever is a simple machine that helps make work easier. A lever is simply a rigid beam that sits on a pivot point called a fulcrum. The lever is a very useful tool when moving or lifting heavy loads. The lever can create mechanical advantage and is also very useful in machines to change the direction of motion. Let’s look at the basic parts of a lever system.
Parts of a Lever
Beam Load 1
Load 2
Fulcrum
How Does a Lever Work?
There are three classes of levers: the first class, second class, and third class levers. The difference depends on where the fulcrum point is positioned. The girls sitting on the seesaw can balance their weight by moving closer or farther away from the fulcrum point. There are countless uses for levers and they are used in almost every machine in some way. This lesson will teach you the basics of how levers work and how they can be used in real life situations.
5
Science Concepts What is a Lever?
There are times we need to lift a heavy object that is too much to do with muscles alone. The mass of the object and the gravitational force on the object must be overcome in order to lift the object.
Gravity (resistance)
Effort Lever Arm
Load
(resistance/ mass)
The lever is a simple machine that is capable of lifting heavy loads by using mechanical advantage. Mechanical advantage is achieved by placing a fulcrum (pivot point) at a location on the lever arm that requires less effort to lift the object than by just using your muscles alone.
Fulcrum Load
(resistance/ mass)
Lever Arm
Effort
Classes of Levers
There are three classes of levers. First and second class levers provide mechanical advantage based on the location of the load, the fulcrum, and the effort, while a third class lever provides additional force and momentum.
First Class Lever
Fulcrum
Second Class Lever
Effort
Load
Lift
Third Class Lever
Load
(resistance/mass)
Load
(resistance/mass)
Fulcrum
Fulcrum
(resistance/mass)
Effort
Fulcrum
Load
(resistance/mass)
Effort
Load
Fulcrum
Fulcrum Effort
(resistance/mass)
Fulcrum
Effort
Effort Load
(resistance/mass)
6
Technology & Engineering Using Levers
Levers are a very important simple machine and are used in many different ways. You probably use levers each day without even realizing it. A lever can be used to lift, move, control, and connect things. Can you think of some common uses of the lever around your house or school?
Lever Examples
Some other common uses of levers are fishing poles, brooms, hand carts,and railway crossings. The shifter on your car is a lever and helps you change gears. Examples of common lever systems are shown below:
Car Shifter Lever
Oil Derrick
Hammer
Hockey Stick
Scales
Wheelbarrow
Lifts
Let’s Build a Lever System
One of the best ways to learn about a lever system is to actually build one. You will be making three working models that will help you understand how each class lever system can create mechanical advantage and make work easier.
7
Build Plan: First Class Lever STEM-Maker Build: First Class Lever
Follow the step-by-step instructions to build a first class lever.
1
Build the Base
Components
4x 2x 3x
2
Build Vertical Support Components
2x
4x
2x
1x
2x
1x 8
Build Plan: First Class Lever 3
Attach Pulleys and Fulcrum Hinge Components
2x 1x
4
Attach Lever Arm Fulcrum Components
2x
2x
1x
1x
9
Build Plan: First Class Lever 5
Attaching Effort Knob to Lever Arm Step 1
Step 2
Cut off a piece of string that is 56cm long. Disconnect the 30˚ angle block and place string between angle block and connector block. Snap the 30˚ angle block back into place to secure string.
NOTE: Section of build has been removed in drawing, only to show better view of lever.
Step 2
Assemble a knob using the components listed below. Place the other end of the string between the single snap block and the connector block. Hang the knob over the top pulley as shown. Components
Angle Block
Step 1
1x
6
1x
1x
Identify Components of Lever Instructions
Pull down on the effort knob to activate the lever.
Effort
Load
Fulcrum
10
Build Plan: Second Class Lever STEM-Maker Build: Second Class Lever
Follow the step-by-step instructions to build a second class lever.
1
Build the Base
Components
4x 2x 3x
2
Build Vertical Support Components
2x
4x
2x
1x
2x
1x 11
Build Plan: Second Class Lever 3
Attach Pulleys and Fulcrum Hinge Components
1x 1x
4
Attach Lever Arm to Fulcrum Components
2x
1x
1x
1x
12
Build Plan: Second Class Lever 5
Attaching Effort Knob to Lever Arm
Step 1
Cut off a piece of string that is 36cm long. Disconnect the 30˚ angle block from the lever arm place string between single snap and connector block as shown. Snap the 30˚ angle block back on the lever arm to secure string.
Step 2 NOTE: Section of build has been removed in drawing, only to show better view of lever.
Step 2
Assemble a knob using the components listed below. Place the other end of the string between the single snap block and the connector block. Hang the knob over the top pulley as shown. Components
Angle Block
Step 1
1x
6
1x
1x
Identify Components of Lever Instructions
Pull down on the effort knob to activate the lever.
Effort
Load Fulcrum
13
Build Plan: Third Class Lever STEM-Maker Build: Third Class Lever
Follow the step-by-step instructions to build a third class lever.
1
Build the Base Components
4x 2x 3x 1x
2
Build Vertical Support Structure Components
2x
4x
2x
1x 2x 14
Build Plan: Third Class Lever 3
Attach Pulleys and Fulcrum Hinge Components
1x 1x
4
Attach Lever Arm Fulcrum Components
2x
1x
1x
1x
15
Build Plan: Third Class Lever 5
Attaching Effort Knob to Lever Arm
Step 1
Cut off a piece of string that is 48cm long. Disconnect the 30˚ angle block and place string between single snap and lever arm as shown. Snap the 30˚ angle block back into place to secure string.
Step 2 NOTE: Section of build has been removed in drawing, only to show better view of lever.
Step 2
Assemble a knob using the components listed below. Place the other end of the string between the single snap block and the connector block. Hang the knob over the top pulley as shown. Components
1x
1x
6
Angle Block
Step 1
1x
Identify Components of Lever
Instructions
Pull down on the effort knob to activate the lever.
Effort
Load
Fulcrum
16
Math Concepts Calculating Mechanical Advantage
Mechanical advantage with a lever is achieved by the positioning of the fulcrum point relative to each side of the lever. To determine the mechanical advantage for each type of lever, use the math formulas shown below:
First Class Lever
Second Class Lever
Effort
Load
Third Class Lever
Load
(resistance/mass)
Load
(resistance/mass)
1cm
(resistance/mass)
3cm
(output)
(input)
25cm (input)
5cm
Effort
(output)
MA =
Fulcrum
Fulcrum
Input Distance (25) =5 Output Distance (5)
With a mechanical advantage of 5, you could lift 5 times your mass by sitting on the 25cm long side. If you weighed 125lbs and sat on the long side of the fulcrum, how much weight could you lift? 125 (input) X 5 (MA) = _____
MA =
Effort
Fulcrum
Input Distance (3) =3 Output Distance (1)
By pushing up from the input end of the lever with a force of 50 lbs., you can lift 150lbs. of load with a mechanical advantage of 3. If you pushed up the input end of the lever with a force of 20lbs., how much could you lift with MA = 3?
Only first class and second class levers can be used to create mechanical advantage. The third class lever is used to create additional momentum because the load end is a long distance from the fulcrum point.
20 (input) X 3 (MA) = _____
Load
(resistance/mass)
Effort
Load
Effort
(resistance/mass)
Fulcrum
Fulcrum
Fulcrum
Effort Load
(resistance/mass)
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Design Challenge Lever
Design Challenge: Catapult
Now that you have learned all about the lever, it is time to apply the knowledge learned in a creative way. In this challenge, each team must design and engineer a custom catapult. Read carefully through the design brief below, then use the design and engineering process to develop the device.
Design Brief: Scenario
You have been given the task of watching your young nephew and niece for the weekend. To make it a fun time for them, you begin to think of something that they would enjoy and remember.
Design Challenge
Your design challenge is to design and build a catapult device that can throw marshmallows at least eight feet. Your niece and nephew will have a blast shooting marshmallows at a target across the room.
Specifications
The design must meet the following specifications: 1. Catapult should be rubberband-powered. 2. Catapult must be designed to hold a small marshmallow for launching. 3. The catapult should be mobile and fit in a hand easily. 4. With each building component costing $2, the catapult must cost less than $50. 5. The challenge must be completed in the allotted time. 6. Write a short story about your project design and be prepared to share it with your classmates.
Using Resources
Use the building components in the Rokenbok SnapStack Module or Advanced Projects Lab to complete this design challenge.
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Design Process Lever
Design and Engineer Process
To develop a high quality catapult, we will review the process that real designers and engineers use to solve a problem. Each team will work through the steps of the design and engineering process to develop a custom catapult. The graphic below highlights each step that will be covered throughout this activity.
What is the Problem/ Opportunity? Fix and Redesign
1 8
Test the Design
2 DESIGN Process
7
6 Build the Prototype/ Model
Research & Discovery
3
Brainstorm Ideas
4 5
Select Solution
Develop the Plan
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Design Process Lever
Using the Design Process
Carefully consider each step of the design process to develop a high quality design. Step 1:
What is the Problem/Opportunity? Design and build a catapult device that will launch a small marshmallow at least eight feet across the room.
Step 2:
Research and Discovery Check out availability of materials, and how to actually build a catapult that is safe and strong. Look online for examples.
Step 3: Brainstorm Ideas List all the ideas that you have found and then look at the pros and cons for each idea, considering each one carefully before making a final decision. Step 4:
Select a Solution Identify the best solution and move forward with your project.
Step 5:
Develop a Plan Once you have made a decision on which solution you think is the best, then the next step is to put together a good plan for designing and building your project.
Step 6:
Build a Prototype/Model Build a scale model of your design.
Step 7:
Test the Design Once you build your prototype or model, you should test your design to make sure that it meets all specifications.
Step 8 : Fix and Redesign If you have identified any problems or design issues, then go back through the design process to make any needed changes or redesigns. Once corrections have been made, then you can proceed with your project.
20
Design Reflection Lever
Applications of STEM
Designers and engineers use science, technology and engineering, and math to solve complex problems. Let’s look at some of the math and science concepts that were included in this STEM Challenge: Science Concepts - Potential Energy - Leverage and Force Technology and Engineering Concepts - Mechanical Design - Form and Function Math Concepts - Measurements - Costs and Budgets Can you think of other STEM concepts that you learned from this project?
Writing Your Story
After you have completed your project, it is important to tell others what you have learned and experienced. One good way to share is to “write your story” down on paper or on the computer. Some things that you might include are: 1. 2. 3. 4. 5.
What were the ideas that your team brainstormed? Why did you choose the design that you built? What was the most difficult part of your design? What did you enjoy the most about this project? The least? What did you learn about design and engineering by completing this project?
Telling Your Story
One fun way to complete this project is to share with your classmates about your design and about what you learned. Make sure that you speak loudly and clearly so everyone can hear and understand you. Be enthusiastic and answer any questions that might be asked.
21
Presentation Lever
Design Challenge Presentation
When you have completed the design challenge, it should be presented to your teacher and classmates for evaluation. Your grade will be determined by how well you do on all grading critera. These include: Specifications Did you follow the rules? Design Quality Is your project strong and safe? Is it well built? Time Management Did you get your project done on time? Did you use your time wisely? Aesthetics Does your project look good? Is it balanced and proportioned? Story Did you write a good story about building your project? Presentation Did you make a good presentation? Were you interesting or unengaging?
Design Challenge Presentation Assessment Your overall project will be graded on the following criteria: Grading Rubric
8-10 Points
5-7 Points
0-4 Points
Specifications
Meets All Specifications
Meets 80% of Specifications
Does Not Meet Specifications
Design Quality
Excellent Design
Good Design
Poor Design
Time Management
Completed on Time
Completed, Not on Time
Not Completed
Aesthetics
Balanced and Attractive
Somewhat Attractive
Unbalanced Unattractive
Well Written Complete Story
Fairly Written Partial Story
Poorly Written Incomplete
Enthusiastic Complete
Unenthusiastic Partially Done
Unengaging Incomplete
Story Presentation TOTAL POINTS
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Assessment What Have We Learned? 1.
What are the two parts of a lever? a. load and effort b. lever arm and fulcrum c. base and axle d. fulcrum and load
2.
The wheelbarrow is a good example of which type of lever? Load a. first class lever (resistance/mass) b. second class lever Effort c. third class lever d. mobile lever
3.
Use the information below to determine the mechanical advantage of the lever.
Fulcrum
Effort
Load
(resistance/mass)
8 Feet (input)
2Feet (output)
MA =
Input Distance Output Distance
MA = ______ Fulcrum
a. b. c. d.
4.
Which type of lever does not use mechanical advantage, but creates additional momentum? a. first class lever b. second class lever c. third class lever d. motion lever
5.
Prying a nail from a board using a claw hammer would be an example of what type of lever? a. first class lever b. second class lever c. third class lever d. claw lever
50-01123-007
MA = 2 MA = 3 MA = 4 MA = 16
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