E-Day Topic Resource Page

Transcription

1 E-Day Resource E-Day Topic Resource Page Grade 2 Topic Simple Machines Brief Overview/objective: To learn about the variety of simple machines and how they make our lives easier each day. We want to introduce the children to the concept of Newton s Laws of Motion, simple machines and work. This is an introduction not a college course so good, simple, thoughtful, experiential discussions and activities are the goal and the methods! After completing this Enrichment Day, the students will be able to: State Newton s 3 Laws of Motion Identify the six kinds of simple machines. Identify at least 10 simple machines in our every-day world and articulate how those machines make the work of motion easier. Resources in workroom: Simple Machine 3- ring binder (activities, information and more) This is a new topic, and there are few resources available at the moment. Most are found in this resource packet. Use the library (public or PCS) and the internet. As you find good resources and ideas, let us know. Ideas to get you started: Make up a song or chant to help remember Newton s Laws of Motion Divide into 3 groups each group can write, illustrate and demonstrate one of these laws for the rest of the class. Build a list of simple machines we would see in every day life so you re prepared to help the children identify/find them around the school. Bring in a variety of examples of simple machines from home. Have a posterboard labeled with the names of the six kinds of simple machines. Build a visual display for each kind of simple machine by 1. Looking through catalogs for examples of simple machines 2. Looking around the room/school for examples 3. Sorting items you ve brought from home Go on a scavenger hunt and find at least 3 of each kind of simple machine Play a Who Am I? game as a review of simple machines. Do experiments to demonstrate Newton s Laws of Motion Do experiments to demonstrate the function and value of simple machines Use Duplos, Tinkertoys, K Nex or other manipulatives to build simple or complex machines. PERIMETER SCHOOL E-DAY RESOURCE last updated

2 Before you can understand the workings of simple machines, you will need to know a bit about movement. Everything around you is moving. In fact, YOU are rotating with the Earth this very minute! All movement is governed by certain mechanical principles. Learning about these mechanical principles will help you understand mechanical movement. Sir Isaac Newton was a great English scientist who was the first to explain the laws of gravity. A legend says he made his discovery as he saw an apple fall from a tree. Newton put forth a variety of laws which explain why objects move (or don't move) as they do. These three laws have become known as Newton's Laws of Motion. Newton's First Law of Motion: "An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless some force interferes with its motion." Basically this means that any moving object will continue in a straight line and at the same speed unless some force interferes with its motion. As an example, if you leave your socks on the floor when you go to bed at night, they will still be in the same spot in the morning unless an outside force moves them. This also means that when you kick a soccer ball it will continue moving until it hits something. However, in reality the ball will slow to a stop even if it does not hit anything because of the friction between the ball and the ground drains its energy. Newton's Second Law: "The greater the force, the greater the acceleration." The second law says it is easier to push the empty cardboard box yourrefrigerator came in than the refrigerator. The mathematical formula for Newton's Second Law says that force is equal to mass times acceleration. This formula is useful because it tells the exact relationship between the different quantities. For example, if you double the amount of mass, it will take twice the force to give it the same acceleration. If any of the two quantities in the formula are known, the other can be figured out. Mass is often confused with weight. Mass is the resistance to being accelerated and weight is the force of the earth's gravity pulling on an object. Acceleration is produced when a force acts on a mass. The greater the mass the greater the amount of force needed (to accelerate the object). In other words, a force acting on a moving object will speed it up, slow it down, or change the direction in which it is moving. A force can also cause an object at rest to start moving. Newton's Third Law: "For every action, there is an equal and opposite reaction." So, if an object is pushed or pulled, it will push or pull equally in the opposite direction. For example, a car has four wheels which spin backwards. As the wheels spin backwards, they push the road backwards. In turn, the road reacts by pushing the wheels forward. The size of the force on the road equals the size of the force on the car's wheels; the direction of the force on the road (downwards) is opposite the direction of the force on the wheels (upwards). For every action, there is an equal and opposite reaction. Action-reaction force pairs make it possible for your car to move. PERIMETER SCHOOL E-DAY RESOURCE [2 of 6] last updated

3 A machine is a tool used to make work easier. Simple machines are simple tools used to make work easier. Compound machines have two or more simple machines working together to make work easier. In science, work is defined as a force acting on an object to move it across a distance. Pushing, pulling, and lifting are common forms of work. Furniture movers do work when they move boxes. Gardeners do work when they pull weeds. Children do work when they go up and down on a see-saw. Machines make their work easier. The furniture movers use a ramp to slide boxes into a truck. The gardeners use a hand shovel to help break through the weeds. The children use a see-saw to go up and down. The ramp, the shovel, and the seesaw are simple machines. Inclined Plane A plane is a flat surface. For example, a smooth board is a plane. Now, if the plane is lying flat on the ground, it isn't likely to help you do work. However, when that plane is inclined, or slanted, it can help you move objects across distances. And, that's work! A common inclined plane is a ramp. Lifting a heavy box onto a loading dock is much easier if you slide the box up a ramp--a simple machine. Wedge Instead of using the smooth side of the inclined plane, you can also use the pointed edges to do other kinds of work. For example, you can use the edge to push things apart. Then, the inclined plane is a wedge. So, a wedge is actually a kind of inclined plane. An axeblade is a wedge. Think of the edge of the blade. It's the edge of a smooth slanted surface. That's a PERIMETER SCHOOL E-DAY RESOURCE [3 of 6] last updated

4 wedge! Screw Now, take an inclined plane and wrap it around a cylinder. Its sharp edge becomes another simple tool: the screw. Put a metal screw beside a ramp and it's kind of hard to see the similarities, but the screw is actually just another kind of inclined plane. How does the screw help you do work? Every turn of a metal screw helps you move a piece of metal through a wooden space. And, that's how we build things! Lever Try pulling a really stubborn weed out of the ground. You know, a deep, persistent weed that seems to have taken over your flowerbed. Using just your bare hands, it might be difficult or even painful. With a tool, like a hand shovel, however, you should win the battle. Any tool that pries something loose is a lever. A lever is an arm that "pivots" (or turns) against a "fulcrum" (or point). Think of the claw end of a hammer that you use to pry nails loose. It's a lever. It's a curved arm that rests against a point on a surface. As you rotate the curved arm, it pries the nail loose from the surface. And that's hard work! Wheel and Axle The rotation of the lever against a point pries objects loose. That rotation motion can also do other kinds of work. Another kind of lever, the wheel and axle, moves objects across distances. The wheel, the round end, turns the axle, the cylindrical post, causing movement. On a wagon, for example, the bucket rests on top of the axle. As the wheel rotates the axle, the wagon moves. Now, place your pet dog in the bucket, and you can easily move him around the yard. On a truck, for example, the cargo hold rests on top of several axles. As the wheels rotate the axles, the truck moves. Pulley Instead of an axle, the wheel could also rotate a rope or cord. This variation of the wheel and axle is the pulley. In a pulley, a cord wraps around a wheel. As the wheel rotates, the cord moves in either direction. Now, attach a hook to the cord, and you can use the wheel's rotation to raise and lower objects. On a flagpole, for example, a rope is attached to a pulley. On the rope, there are usually two hooks. The cord rotates around the pulley and lowers the hooks where you can attach the flag. Then, rotate the cord and the flag raises high on the pole. If two or more simple machines work together as one, they form a compound machine. Most of the machines we use today are compound machines, created by combining several simple machines. Can you think of creative ways to combine simple machines to make work easier? Think about it. PERIMETER SCHOOL E-DAY RESOURCE [4 of 6] last updated

5 MACHINES AT HOME AND AT SCHOOL LEVERS Not all long, skinny objects are levers. A lever is a simple machine so to be a lever it must use energy to move a load. Can you find three levers in your home or classroom? WHEELS Cars have wheels, of course! Four of them. Wrong! Cars have dozens and dozens of wheels. Remember that rollers, gears, and pulleys are all types of wheels. Find at least five different types of wheels in or on your car. INCLINED PLANES Find at least three things that screw. Which direction (clockwise or counterclockwise) do they turn to open or get longer? OBJECT DIRECTION PERIMETER SCHOOL E-DAY RESOURCE [5 of 6] last updated

6 Name: DAILY DOINGS WITH SIMPLE MACHINES How many times do you use simple machines during the day? Make an estimate and fill in the blank below. My Estimate I think I use simple machines times a day. Record of Simple Machine Use Write down the name of each object you use and what type of simple machine it is. Then put a checkmark next to the name of each simple machine every time you use it. You may attach another sheet of paper to this worksheet if needed. Add all your checkmarks up at the end of your day! Object Used Type of Simple Machine Times Used Total Example: Curtain Cord Pulley x x 2 Your Results Did you use simple machines more or less often than you estimated you would? PERIMETER SCHOOL E-DAY RESOURCE [6 of 6] last updated