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1. Simple Machines .ppt all about machines
- 1. By the endyou will be able to: • describe the relationship between energy and work • explain how the six simple machines operate • provide reasons why more energy-efficient machines are needed • analyze the output of simple machines Mingun Temple – Irriwaddy River
- 3. Simple machines wereused to move large limestone blocks for the Egyptian pyramids... The Great Pyramid near Cairo
- 4. …and the Moaistatues of Easter Island many kilometres from the quarries where they were carved out.
- 5. Energy, work andforce are all involved in rock climbing. What kinds of energy? What kinds of forces? How much work?
- 6. Energy – theability to do work Work = Force x distance (or W = F x d) Force (effort)– a push or a pull Force is measured in Newtons (N). Distance is measured in metres (m). Therefore, energy is the ability to move a mass using a push or pull.
- 7. Work ismeasured in Newton-metres (N•m) or Joules (J). Energy is also measured in Joules. Work is only done when both these conditions exist: 1) a force is applied, and 2) the object moves. A person coasting on a skateboard or bike is not doing work; BUT pushing off or pedaling classifies as work. A student studying does no work but a student writing an essay does… as long as the pen keeps moving.
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- 9. A simple machinehas few or no moving parts. Simple machines make work easier
- 10. Simple machines makework easier to do. They decrease the effort force. Simple machines don’t create less work, they just spread the force applied over a greater distance.
- 11. Types of SimpleMachines 1) wheel and axle 2) pulley a) moveable b) fixed 3) inclined plane (ramp) 4) wedge 5) screw 6) lever a) first class b) second class c) third class a “declined plane”
- 12. The wheeland axle are a simple machine The axle is a rod that goes through the wheel which allows the wheel to turn Gears are a form of wheels and axles
- 13. Wheel and Axle –a larger wheel turning a smaller wheel Examples: door knob screwdriver wrench bike sprocket Winch Turning a large wheel takes less effort than turning a small wheel. This decreases effort force and multiplies applied force. The large wheel moves through a greater distance than the smaller wheel, spreading effort over a longer distance.
- 14. Pulley arewheels and axles with a groove around the outside A pulley needs a rope, chain or belt around the groove to make it do work
- 15. pulley – agrooved wheel A pulley threaded with a rope is a simple machine. Effort occurs at one end (pull) while the load moves at the other end (push). equilibrium – a system in balance e.g. when the effort just supports the load (pull = push)
- 16. The number ofwheels on the pulley determines the effort force that is needed: 1 wheel = 1/1 effort 2 wheels = ½ effort 3 wheels = 1/3 effort Fixed pulley – effort force equals the load force; the fulcrum does not move example: clothesline The load is still easier to move because pulling down and inward is easier than pushing up against the force of gravity. Moveable pulley – the pulley moves with the load example: block and tackle Complex machines are made by combining simple
- 17. Sailing block andtackle Sails are hard to hoist against the force gravity and the wind.
- 18. An inclinedplane is a flat surface that is higher on one end Inclined planes make the work of moving things easier
- 19. It isa flat surface whose endpoints are at different heights. By moving an object up an inclined plane rather than completely vertical, the amount of force required is reduced, The negative is the increasing distance the object must travel. Examples of Inclined Planes game trail switchback exit ramp ski hill
- 20. Two inclined planesjoined back to back. Wedges are used to split things.
- 21. Wedge wedge – tworamps that meet at a point A wedge changes the direction of force. Examples of Wedges doorstop knife axe snap button nail shoe scissors effort force
- 22. A screwis an inclined plane wrapped around a shaft or cylinder. The inclined plane allows the screw to move itself when rotated.
- 23. Screw Examples of Screws screw-topbottle wood screw cork screw A screw is basically a ramp wrapped around a cylinder. What are the differences between a metal and a wood screw?
- 24. lever – abar that pivots All levers have the following five parts: fulcrum – a pivot point load – the mass that is moved effort – where the force is applied load distance – the distance from the fulcrum to the load effort distance – the distance from the fulcrum to the effort example: light switch
- 25. In afirst class lever the fulcrum is in the middle and the load and effort is on either side Think of a see-saw
- 26. First Class Lever Thefulcrum is in the middle: L F E or E F L Examples teeter-totter scissors screwdriver used to pry off a lid triceps muscle used to push a load The mechanical advantage is the reduction in effort (for lifting, prying and cutting).
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- 29. Which class oflever is this wood clamp? load fulcrum effort
- 30. In asecond class lever the fulcrum is at the end, with the load in the middle Think of a wheelbarrow
- 31. Second Class Lever Theload is in the middle: F L E or E L F Examples wheelbarrow nutcracker The mechanical advantage is in being able to move heavier loads.
- 32. In athird class lever the fulcrum is again at the end, but the effort is in the middle Think of a pair of tweezers
- 33. Third Class Lever Theeffort is in the middle: F E L or L E F Examples fishing rod with reel broom tweezers racket, bat or stick biceps muscle lifting a load in your hand The mechanical advantage is in speed.
- 34. Fisherman on theBow River in Calgary
- 35. distance multiplier –a simple machine that moves a load through a large distance with short effort distance e.g. third class lever Example: hockey stick used for a slap shot force multiplier – a simple machine that requires a small effort force to move a massive load e.g. first and second class lever Example: crowbar used to open a door
- 36. Simple Machinescan be put together in different ways to make complex machinery
- 37. • https://www.youtube.com/watch?v=Ss-P4qLLUyk • http://www.youtube.com/watch?v=YWk9N92-wvg •https://www.youtube.com/watch?v=qybUFnY7Y8w
Editor's Notes
- #18 A sloping surface, such as a ramp. An inclined plane can be used to alter the effort and distance involved in doing work, such as lifting loads. The trade-off is that an object must be moved a longer distance than if it was lifted straight up, but less force is needed. You can use this machine to move an object to a lower or higher place. Inclined planes make the work of moving things easier. You would need less energy and force to move objects with an inclined plane.