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# Levers, Wheels And Axles, Pulleys

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### Levers, Wheels And Axles, Pulleys

1. 1. Levers 1 st Class Levers 2 nd Class Levers 3 rd Class Levers
2. 2. What is a Lever? <ul><li>A lever is a simple machine that is used to lift things. </li></ul><ul><li>It is made up of a bar (called the lever stick) and a support (called the fulcrum). </li></ul>Lever Stick Fulcrum
3. 3. Everyday Examples of Levers <ul><li>See-Saw </li></ul><ul><li>Nutcracker </li></ul><ul><li>Wheelbarrow </li></ul><ul><li>Broom </li></ul><ul><li>Can you think of any more? </li></ul>
4. 4. Parts of a Lever <ul><li>There are different parts and sections of a lever. </li></ul><ul><li>You have the fulcrum and lever stick. </li></ul><ul><li>You also have a force side and a load side. </li></ul><ul><li>The relationship between the position of the load side, fulcrum, and force side determines what class of lever it is. </li></ul>
5. 5. Classes of Levers <ul><li>There are three different classes of levers. </li></ul><ul><ul><li>1 st Class: force side-fulcrum-load side </li></ul></ul><ul><ul><li>2 nd Class: force side-load side-fulcrum </li></ul></ul><ul><ul><li>3 rd class: load side-force side-fulcrum </li></ul></ul>
6. 6. 1 st Class Lever <ul><li>Structure of the 1 st Class Lever: </li></ul><ul><ul><li>Force Side-Fulcrum-Load Side </li></ul></ul><ul><li>The see-saw is an example of a first class lever. </li></ul><ul><li>The force needed to lift the load decreases when the fulcrum gets closer to the load side. </li></ul>
7. 7. 2 nd Class Lever <ul><li>Structure of a 2 nd Class Lever </li></ul><ul><ul><li>Force Side-Load Side-Fulcrum </li></ul></ul><ul><li>The wheelbarrow and the nutcracker are examples of a 2 nd class lever. </li></ul><ul><li>Again, The force needed to lift the load decreases when the fulcrum gets closer to the load side. </li></ul>
8. 8. 3 rd Class Lever <ul><li>Structure of a third class lever </li></ul><ul><ul><li>Load Side–Force Side–Fulcrum </li></ul></ul><ul><li>The broom is an example of a 3 rd class lever. </li></ul><ul><ul><li>The load is the dirt or end of the broom, the force is your bottom arm, and the fulcrum is your top hand. </li></ul></ul>
9. 9. What type of lever am I (1,2,or3)? 1 st Class 1 st Class 2 nd Class 2 nd Class 3 rd Class 3 rd Class
10. 10. Wheels and Axles Wheel and Axle
11. 11. What is a Wheel & Axle? <ul><li>A wheel and axle is a simple machine consisting of a wheel that revolves (turns) around a post (axle). </li></ul><ul><li>This simple machine makes it easier for us to move things from one place to another. </li></ul><ul><li>The further the force is away from the axle, the easier it is to turn the wheel. This means that it is easier to turn a big wheel than a small wheel. </li></ul>
12. 12. Pictures of Wheels and Axles
13. 13. Common Examples
14. 14. Pulleys Fixed Pulley Movable Pulley Block and Tackle
15. 15. What is a Pulley? <ul><li>Pulleys are a kind of simple machine that consists of a rope that fits onto a wheel and changes the direction of a force. </li></ul><ul><li>There are three kinds of pulleys. </li></ul><ul><ul><li>Fixed Pulley </li></ul></ul><ul><ul><li>Movable Pulley </li></ul></ul><ul><ul><li>Block and Tackle (combo of fixed and movable) </li></ul></ul>
16. 16. Fixed Pulley <ul><li>Wheel attached to surface </li></ul><ul><li>Changes the direction of the applied force </li></ul><ul><li>NO mechanical advantage – same amount of force is required </li></ul>
17. 17. Movable Pulley <ul><li>Pulley moves along the rope </li></ul><ul><li>Wheel supports the load </li></ul><ul><li>Effort is in the same direction as movement </li></ul><ul><li>Reduces the forces needed to move an object </li></ul>
18. 18. Block and Tackle <ul><li>Has at least two wheels (one movable and one fixed) </li></ul><ul><li>The more complex the pulley, the more the effort needed to move the object decreases </li></ul>
19. 19. Common Examples Of Pulleys