Week 9 putting machines together
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This document outlines lesson plans for teaching 8th grade students about simple machines over the course of a week. The lessons cover pulleys, wheels and axles, and compound machines. Students will learn how to calculate mechanical advantage, describe how each machine works, and combine simple machines into compound machines. Assessment includes worksheets, quizzes, and activities to reinforce understanding of how simple and compound machines make work easier to do.
Week 9 putting machines together
- 1. 8th Grade Simple Machines Using Turning Monday, October 21 Objective: Students will… Describe and calculate the mechanical advantagesof pulleys and wheels. Essential Question: How does a pulley make use of turning? Introduction: Watch https://bit.ly/2KNfqEB Instructions: Turn to page 92-93 1. Look at the three images at the bottom of page 93 and identify which ones use pulleys. 2. Explain why the pulleys in these pictures make moving objects easier. 3. Look at the types of pulleys on page 94; explain what makes the fixed pulley different from the movable pulley and the block and tackle. 4. The ideal mechanical advantage of a pulley, or pulley system, is equal to the number of sections of rope that support the object. Look at the painter in the picture on page 94 and determine the mechanical advantage of this pulley system. 5. Explain the mechanical advantage of combining fixed and movable pulleys in s system like this one. 6. Summarize how do pulleys use wheels to make lifting heavy objects easier (discuss mechanical advantages of pulleys and pulley systems). 8th Grade Wheel and Axle Tuesday, October 22 Objective: Students will… Describe the how a wheel and axle works. Essential Question: How does a wheel and axle work? Introduction: Watch Ideal mechanical Advantage = Radius ofWheel Radius of axle Instructions: Turn to page 95 and… 1. Draw the wheeland axle diagram showing the direction of input and output forces,the wheel radius and axle radius. 2. Explain how the screwdriver acts as a wheel and axle; which end receives the smaller input force and outputs the larger force? 3. Look at the blue screwdriver, on page 95, which has a handle radius of 1.5 cm and a shaft radius of 0.25 cm. Calculate its mechanical advantage. 4. List two examples of a wheel and axle. Which of your examples has the greater mechanical advantage and why? 5. You exert a 100-N force on a pulley system to lift 300 N. What’s the mechanical advantage of this system? How many sections of rope support the weight? 6. Summarize the mechanicaladvantage of the wheel and axle and how do these combine to make work easier?
- 2. 8th Grade Compound Machines Wednesday, October 23 Objective: Students will… Describe how compound machines work. Essential Question: Where do the input and output forces go, in compound machines? Introduction: Watch Within a compound machine, the output force of one simple machine becomes the input force of another simple machine Think about a stapler. The handle is a lever. Each tip of a staple acts as a wedge. Suppose the lever has a mechanical advantage of 0.8 and the wedge has a mechanical advantage of 2. If you input a force of 10 N on the lever, the output force of the lever will be 8 N. That 8 N becomes the input force of the wedge,and the final output force is 8 N times 2, or 16 N. Instructions: Turn to page 96 1. Look at the photo of the apple peeler, on page 96. If the mechanical advantages of the component machines in the peeler are 2, 3 and 12, what is the overall mechanical advantage of the apple peeler? 2. Look at page 97-Calculate the mechanical advantage of each simple machine in the compound machine. The simple machine mounted on the truck has an inner radius of 0.05 m and an outer radius of 0.25 m. What is the overall mechanical advantage? 3. Calculate the mechanical advantage of a pencil sharpener made from a wheel and axle with a mechanical advantage of 3 and a wedge with a mechanical advantage of 4. What is the MA? 4. Summarize- how simple and compound machines make it easier to do work. Study the Quizlet found here: https://quizlet.com/_7c239y 8th Grade Compound Machines Thursday, October 24 Objective: Students will… Review and reinforce calculating the mechanical advantage of compound machines Essential Question: What do we rememberabout the MA of compound machines? Instructions: Students will… Work in small pairs to find the answers to the handout questions for “Assess Your Understanding” and “Review and Reinforce”,followed by “Enrich”. Friday- Students will review by answering the “Lesson Quiz” handout questions. Take the Quizlet found here: https://quizlet.com/_7c239y