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Simple Machines and Their Mechanics

Learn about different types of simple machines such as levers, pulleys, wheel and axle, gears, inclined planes, screws, wedges, and compound machines. Discover their mechanical advantage and how they can be used to perform work efficiently.

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Simple Machines and Their Mechanics

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  1. Simple Machines -a machine that does work with one movement

  2. Levers • A bar that is free to pivot, or turn, about a fixed point • Fulcrum- fixed point on the lever • Input arm- part of lever that person adds input force to • Output arm- part of lever that moves the output force or work

  3. 3 types of Levers

  4. First class lever • Fulcrum is located between the input force and the output force • screwdriver opening paint can • Fulcrum?

  5. Second class lever • Ouput force is located between the input force and the fulcrum • Wheel barrow Output force fulcrum Input force

  6. Third class lever • Input force is located between the output force and the fulcrum • Baseball bat, rake, hockey stick fulcrum Output arm Input arm

  7. Mechanical advantage of lever • MA = length of input arm = Li length of output arm Lo

  8. Homework • Calculate the MA of a wheel barrow that has 5 feet from the wheel to handle. The center of the load is exactly 2.5 feet from the wheel. • What would you do to design a better wheel barrow?

  9. Pulleys • Grooved wheel with a rope, chain, or cable running through the groove • Fixed pulleys • Change direction of force • Gravity Help! • MA = 1

  10. Movable Pulleys • Move when a force is applied. • MA = 2 • Multiply the input force 2x.

  11. Pulley SystemsBlock and Tackle • A system of fixed and movable pulleys • MA = number of ropes supporting the weight • Do not count rope that you pull down on.

  12. Wheel and Axle • Two wheels of different sizes that rotate together • Can you think of any? • Doorknobs • Faucets • Steering wheel • Stereo volume knobs

  13. Gears • Form of wheel and axle • Two wheels of different sizes with interlocking teeth • Multiply the input force and change direction of force

  14. Mechanical advantage of W&A • MA = radius of wheelrw radius of axle ra

  15. Inclined Planes • A sloping surface that reduces the amount of force needed to do work • Ramps • Roads

  16. Mechanical advantage of IP • MA = length of slope l height of slope h h l

  17. Screw • Inclined plane wrapped around a cylindrical post • Wood screws • Soda lids • Olive jars

  18. Wedge • Inclined plane with one or two sloping sides that moves through an object or material to change the direction of the force. • Knives • Axes

  19. Compound Machines • Two or more simple machines working together to perform a task • Scissors • Faucets • Jeeps

  20. Compound machines at work in the classroom. • Goal: to extinguish a candle flame using 4 or more simple machines.

  21. The End Calculations are next!

  22. Calculations • Calculate the Mechanical Advantage of a lever that has an input arm of 15 meters and a output arm of 3 meters. 15 m 3 m fulcrum

  23. MA of levers • MA = length of input arm length of output arm = 15 m 3 m = 5

  24. MA of a Wheel and axle • Calculate the MA of the door knob that you turn as you try to sneak into Mr. Miller’s room tardy. • The knob itself has a radius of 12 cm and the axle that runs through the knob as a radius of 1.2 cm.

  25. MA of W&A = radius of wheel radius of axle = 12 cm 1.2 cm = 10

  26. MA of an Inclined Plane • Calculate the mechanical advantage of an inclined plane/ramp used to load your ATV onto the bed of a truck. • The truck’s bed is exactly 2 meters off the ground and the ramp is 8 meters long.

  27. MA of I.P. = length of ramp height of ramp 8 m MA = 8 m 2 m = 4 2 m

  28. MA of pulleys! 120 N 120 N 120 N 120 N

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