Links to Physical Science Levers and Pulleys Investigation 1: Introduction to Levers Part 2: Notebook Writing: Response Sheet – Levers Randy and Kevin had been working with levers for a couple of days. They were trying new ways to set up levers. They each set up a lever system. Both lever systems had the load hanging at the 40-cm position on one side, and the effort pressing at the 40-cm position on the other side (Investigation Duplication Masters, Student Sheet No.5). Randy said, “Our levers are the same. They will both take the same amount of effort to lift the load.” Kevin responded, “I don’t think so. One of these systems will require less effort to lift the load.” Which student do you think was right? Explain why you think so. (TG Investigation 1, p.23) (TG Assessment, p.2-3) (Investigation Duplication Masters, Student Sheet No.5) Investigation 1: Introduction to Levers Part 3: Activity: Build a Teeter-Totter Bring a long piece of construction lumber (at least a 10-foot long piece of 2 by 6) and a short piece of 4 by 4 (for a fulcrum) to class. Let students have fun working with the lever variables (load, effort, fulcrum) on a human scale. Explore the effect of moving the fulcrum to various locations under the board. Compare the behavior of your lever to a teeter-totter. (TG Investigation 1, p.31) Investigation 1: Introduction to Levers Part 3: Activity: Pull Some Nails Crowbars, wonder bars, or a cat’s-paw nail pullers are levers with the fulcrum between the effort and the load. Bring in a heavy piece of wood (a section of a tree trunk is ideal) and a hammer and some nails. Provide students with some real-world experience pulling nails to appreciate the advantage offered by a lever. (TG Investigation 1, p.31) Investigation 2: More Leverage Part 2: Notebook Writing: Response Sheet – More Leverage Millie and Jasmine were looking at a clothespin. They were pretty sure that the clothespin is a class-1 lever. They analyzed it like this (Investigation Duplication Masters, Student Sheet No.11). When Carrie looked at the clothespin, she said, “When you squeeze the clothespin, it is a class-1 lever, but when it is holding clothes on the line, it is a class-3 lever. Carrie analyzed the clothespin like this (Investigation Duplication Masters, Student Sheet No.11). Do you agree with the girls? Why or why not? Explain your reasoning. (TG Investigation 2, p.17) (TG Assessment, p.8)

Submitted by Carol Olson and Kris Siebers – June, 2007

(Investigation Duplication Masters, Student Sheet No.11) Investigation 2: More Leverage Part 4: Math: Problem of the Week – More Leverage Buddy was working with a class-1 lever. He had a load that pulled with a force of 20 N. He did these three experiments (Investigation Duplication Masters, Student Sheet No. 29). Buddy looked at experiment 1. He looked at the force of the load (20 N) and its distance from the fulcrum (20 cm). Then he looked at the force of the effort (20 N) and its distance from the fulcrum (20 cm). Everything balanced. Buddy looked at experiment 2. The load was at the same location, but now the effort was only 10 N, and it was way out at 40 cm. And everything still balanced. Suddenly Buddy saw something that he thought might be important. He said, “I bet if I move the load 30 cm from the fulcrum, and put the effort 10 cm from the fulcrum, I will have to use an effort of 60N to lift the load!” He set up experiment 3 and discovered that he was right. What did Buddy figure out? Can you predict the effort needed to lift the load on the levers below? (TG Investigation 2, p.26-27) (Investigation Duplication Masters, Student Sheet No.29) Investigation 2: More Leverage Part 4: Activity: Make a Levers Bulletin Board Ask students to bring pictures of levers in action from newspapers and magazines. The objects might be tools, sports equipment, or parts of larger machines. Have students organize them by class and arrange a bulletin board of the pictures. (TG Investigation 2, p.28) Investigation 2: More Leverage Part 4: Activity: Build a Compound Lever Challenge students to use the half-meter sticks and other materials to build a multiple-lever system where one lever acts on another to provide a double advantage. Compare the effort and load in such a system. (TG Investigation 2, p.28) Investigation 2: More Leverage Part 4: Activity: Graph Class-2 Levers Have students put the scale at the end of a class-2 lever (50 cm from the fulcrum). Have them find out how much effort is required to lift the load as it moves from the fulcrum to the effort in 5cm intervals. Ask them to graph the results. (TG Investigation 2, p.28) Investigation 2: More Leverage Part 4: Activity: Graph Class-3 Levers Have students put the scale 10 cm from the fulcrum on a class-3 lever. Have them find out how much effort is required to lift the load as it moves from the position of the effort out to the end of the lever in 5-cm intervals. Ask them to graph the results. (TG Investigation 2, p.28)

Submitted by Carol Olson and Kris Siebers – June, 2007

Investigation 3: Pulleys Part 2: Notebook Writing: Response Sheet – Pulleys Karl told his brother Charles, “I just couldn’t lift that 30-kg bag of cement into Dad’s wheelbarrow until I got a pulley and a rope. Then it was easy.” Charles was surprised. “You got the cement into the wheelbarrow!? How did you do it? How much easier was it?” Explain how you think Karl lifted the cement and how much effort he had to apply. (TG Investigation 3, p.20) (TG Assessment, p.11) (Investigation Duplication Masters, Student Sheet No.19) Investigation 3: Pulleys Part 3: Math: Problem of the Week – Pulleys . . . and then they came to the cliff. A rope was hanging from a single pulley, with a platform attached to the end of the rope. There was no other way up. How would Julie, her mom, her uncle, and her grandfather get to the top of the cliff with Sparky the pony? Julie had studied pulleys in science. She thought about the problem for about 10 minutes and came up with a plan. Can you figure out how to get the whole troop up the cliff? What is the fewest number of lifts that can get the job done? (TG Investigation 3, p.26-27) (Investigation Duplication Masters, Student Sheet No.30) Investigation 3: Pulleys Part 3: Activity: Set up a Pulley Learning Station Set up a learning station. Have students work together to assemble pulley systems that use a single and a double pulley (two wheels, provided in the kit), two single pulleys, and two double pulleys. (Longer ropes will probably be required.) Have them record how many different systems they discover and how much effort is required. (TG Investigation 3, p.28) Investigation 3: Pulleys Part 3: Activity: Do Real Work with Pulleys Get some heavy-duty pulleys and strong rope from a hardware store. Find a suitable location outdoors (tree limb, swing set, etc.) from which to secure fixed pulleys. Have students rig up different pulley systems and experience lifting a heavy load like a bucket of bricks or another student. Provide work gloves for the student doing the work. (TG Investigation 3, p.28) Investigation 3: Pulleys Part 3: Activity: Home/School Connection Students make broomstick-pulley systems and use them to overcome the resistive force of family members trying to prevent the sticks from being pulled together. (TG Investigation 3, p.28) (Investigation Duplication Masters, Student Sheet No.34) Investigation 4: Pulleys at Work Part 2:

Submitted by Carol Olson and Kris Siebers – June, 2007

Notebook Writing: Pulleys at Work Belinda and her mother cut and polished rocks to make beautiful bookends. They pack them in crates for shipment. Each crate has a mass of 20 kg. Belinda can lift only one crate of bookends at a time up to the shipping area. Belinda decided to put together a pulley system to lift the crates up the 2 m to the shipping area. She said, “With this system I will be able to lift six crates at a time. And there is no disadvantage. Using a pulley system is just like getting something for free.” Is Belinda right about the number of crates she will be able to lift? Is her statement right that there is no disadvantage? Explain. (TG Investigation 4, p.20) (TG Assessment, p.14) (Investigation Duplication Masters, Student Sheet No.24) Investigation 4: Pulleys at Work Part 3: Notebook Writing: Research Other Simple Machines If students have not read about the other four simple machines in the FOSS Science Stories, have them find out what they are and give a short report to the class. • “The Wheel and Axle” (Levers and Pulleys; FOSS Science Stories, p.7-9 and TG Science Stories, p.6-7) • “The Inclined Plane” (Levers and Pulleys; FOSS Science Stories, p.14-15 and TG Science Stories, p.12-13) • “The Wedge” (Levers and Pulleys; FOSS Science Stories, p.21-22 and TG Science Stories, p.16-17) • “The Screw” (Levers and Pulleys; FOSS Science Stories, p.26-27 and TG Science Stories, p.20-21) (TG Investigation 4, p.26) Also refer to Machine by Lillian Duggan (Leveled Book, p.8-11). Investigation 4: Pulleys at Work Part 3: Notebook Writing: Research Complex Machines A steam shovel is a complex machine composed of simple machines – levers and pulleys. Have students research steam shovels and other machinery, analyze them in terms of simple machines, and write a report. Here are a few examples of these complex machines; • backhoe • crane • hook-and-ladder truck • drilling rig • elevator • hoist • drawbridge • exercise equipment Investigation 4: Pulleys at Work Part 3: Math: Problem of the Week and Graph Pulley Results Ted and Jan were working on a search-and-rescue team that needed to lower an injured climber down a 20-m cliff. Ted was at the top of the cliff; Jan was at the bottom of the cliff. The injured climber weighed 720 N. They have two pulleys and three ropes in their rescue kit. The ropes are 50 m, 65 m, and 80 m. Scenario A. Ted is going to attach the injured climber to the pulley system and lower him to Jan.

Submitted by Carol Olson and Kris Siebers – June, 2007

• • • •

How should they set up their pulleys so Ted can lower the climber using as little effort as possible? How much effort will Ted have to use? Which is the shortest of their ropes they can use for the job? What is the mechanical advantage?

Scenario B. Ted is going to attach the injured climber to the pulley system, and Jan is going to lower the climber from her position at the bottom of the cliff. • How should they set up their pulleys so Jan can lower the climber using as little effort as possible? • How much effort will Jan have to use? • Which is the shortest of their ropes they can use for the job? • What is the mechanical advantage? NOTE: Mechanical advantage = Load divided by effort Have students use centimeter graph paper to graph the results of their investigations. • The number of supporting ropes (x-axis) versus the effort required to lift the load. • The number of supporting ropes (x-axis) versus the distance the rope is pulled. (TG Investigation 4, p.26-27) (Investigation Duplication Masters, Student Sheet No.31) Investigation 4: Pulleys at Work Part 3: Activity: Try a Different Approach with Two Pulleys Challenge students to assemble a pulley system using two single pulleys that will give a 4:1 mechanical advantage. Usually 3:1 is the greatest advantage obtained from two single pulleys. Let interested students work at this problem – it can be done. This is called a Spanish Barton system. The solution is diagrammed on page 7 (TG Investigation 4, p.7). (TG Investigation 4, p.27) Investigation 4 Pulleys at Work Part 3: Activity: Set Up Complex Systems Challenge students to set up a lever-and-pulley system in which a pulley is used to apply effort to one end of a lever that in turn lifts a load. This is the gateway to complex machines, in which two or more simple machines work together. Have students compare effort and distance. (TG Investigation 4, p.27)

Submitted by Carol Olson and Kris Siebers – June, 2007