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Simple Machines

Simple Machines. There are a total of 6 simple machines. Simple Machines. Inclined Planes.

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Simple Machines

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  1. Simple Machines • There are a total of 6 simple machines

  2. Simple Machines • Inclined Planes. • A plane surface set at an angle, other than a right angle(not °90),against a horizontal surface. The inclined plane permits one to overcome a large resistance by applying a relatively small force through a longer distance than the load is to be raised. • Examples: Ramps, chisels, hatchets, plows and carpenter's planes.

  3. Simple Machines • Inclined Planes Applied Force Friction Mass * gravity or Weight

  4. Simple Machines • Screw • A screw is an inclined plane wrapped around a pole which holds things together or lifts materials.

  5. Simple Machines • Screw

  6. Simple Machines • Wedge • Consists of a pair of inclined planes set back-to-back. It performs its work by moving. In contrast, the inclined plane always remains stationary.

  7. Simple Machines • Wedge Two inclined planes joined back-to-back

  8. Simple Machines • Pulley • A simple machine consisting essentially of a wheel with a grooved rim in which a line (rope, chain, cord, etc) can run to change the direction of the pull and thereby lift a load.

  9. Simple Machines • Pulley • block and tackle • an arrangement of one or more pulley blocks, with rope or cables, providing significant mechanical advantage for pulling or hoisting large, heavy objects

  10. Simple Machines • Pulley http://discover.edventures.com/functions/termlib.php?action=&single=&word=block+and+tackle

  11. Simple Machines • Wheel and Axle • A wheel and axle is a lever that rotates in a circle around a center point or fulcrum. • The mechanical advantage of a wheel and axle is the ratio of the radius of the wheel to the radius of the axle. If the radius of the wheel is four times greater than the radius of the axle, every time you turn the wheel once, your force will be multiplied four times.

  12. Simple Machines • Wheel and Axle http://www.northallegheny.org/schools/mms/TSA%202006/TSA2007/Wheel%20and%20Axle.html

  13. Simple Machines • Levers • Levers are one of the simple machines that were probably used in prehistoric times. Levers were first described about 260 BC by the ancient Greek mathematician Archimedes (287-212 BC).

  14. Simple Machines • A lever is a simple machine that makes work easier for use; it involves moving a load around a pivot using a force. Many of our basic tools use levers, including scissors (2 class 1 levers), pliers (2 class 1 levers), hammer claws (a single class 2 lever), nut crackers (2 class 2 levers), and tongs (2 class 3 levers).

  15. Simple Machines • In physics, a lever is a rigid object that is usedwith an appropriate fulcrum or pivot point to multiply the mechanical force that can be applied to another object.

  16. Simple Machines • The lever allows less effort to be expended to move an object a greater distance.

  17. The three classes of levers • A first-class lever is a lever in which the fulcrum is located in between the input force and the output force.

  18. Class 1 levers • Examples: #Seesaw (also known as a teeter-totter) • 1. Crowbar or claw hammer (removing nails) • 2. Pliers (double lever)

  19. The three classes of levers • In a second-class lever the input is located to the far side of the bar, the output is located in the middle of the bar, and the fulcrum is located on the side of the bar opposite to the input.

  20. Class 2 Levers • # Wheelbarrow • # Nutcracker • # Door • # Pry bar • # Stapler • # Diving board

  21. The three classes of levers • Class 3 levers. The input effort is higher than the output load. However, also notice that the input effort moves through a shorter distance than the output load.

  22. The Lever Lab • To determine how levers change the force required to move an object.

  23. Way Cool Levers • The trebuchet is a counterweight siege engine. Basically, alever and a sling.

  24. But First!………...

  25. A bit about Siege Engines • Basically there are three ways to power a machine that throws a projectile. • Flexion • Torsion • Levers

  26. A bit about Siege Engines • Flexion • Which is thebending of a limb or leaf spring. • Bows, crossbows, and the most ancient of large Greek rock throwing and arrow throwing siege engines were Flexion. • The gastrophetes was the firstrecorded arrow throwing siege engine showing up around 399 BC.

  27. A bit about Siege Engines

  28. A bit about Siege Engines

  29. A bit about Siege Engines • Torsion • They have arms similar to the limb of a bow on a crossbow, but the arms are independently powered by bundles of semi-flexible sinew cord wrapped into a frame of wood which are pretensioned and then twisted. • Recorded first around 250 BC.

  30. A bit about Siege Engines

  31. A bit about Siege Engines • The two-armed ballista and catapulta invented by the Greeks and later used by Romans was largely replaced by the Roman onager, which was a much simpler design, using only one arm to propel a rock with a sling.

  32. A bit about Siege Engines

  33. A bit about Siege Engines • In the early Middle Ages, walls and fortifications had become taller and stronger than they ever were in ancient Greek times, and the stone castle was developed, which had walls stronger than most ancient siege engines could destroy.

  34. A bit about Siege Engines • From the Mongolians in the east came the idea for a new type of siege engine, powered by gravity and designed for one purpose; to destroy walls. This was the trebuchet.

  35. Trebuchet • The trebuchet is a Type-1 lever and a sling. In the Type-1 lever, the force is applied to one end, the load is on the other end and the fulcrum sits between the two.

  36. Trebuchet • The sling is the oldest projectile weapon. There is a pouch to hold the projectile and two long strings. Both ends of the string are held in one hand and the sling is swung around and around. Then, at the proper moment, one end of the sling is let go with the other end is still held by the hand

  37. Trebuchet

  38. Historic Counterweight Trebuchet Illustrations Trebuchet from The Romance of Alexander (circa 1330).

  39. Historic Counterweight Trebuchet Illustrations Trebuchet by Kolderer, c1507.

  40. Historic Counterweight Trebuchet Illustrations An early 14th Century trebuchet

  41. Historic Counterweight Trebuchet Illustrations A 13th Century "Mongol" trebuchet

  42. Historic Counterweight Trebuchet Illustrations A fixed-weight trebuchet from the early 16th Century

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