Explore mechanics.im
simple-machines.mechanics.im
Every fact

113 facts, every one sourced

Every fact on this site in one list, each linked to its source. Our build stores the source text and checks that the key words and figures in each fact really appear in it; see the sources page.

  1. 1 A simple machine is a device with few or no moving parts that changes the size or direction of a force so that a job gets done. Britannica
  2. 2 Britannica lists six simple machines: the inclined plane, the lever, the wedge, the wheel and axle, the pulley and the screw. Britannica
  3. 3 Britannica’s own articles on the pulley and the wedge call each of them one of “the five simple machines”, a list without the inclined plane. Britannica
  4. 4 A US Navy training manual also counts six, but a different six: the lever, the block, the wheel and axle, the inclined plane, the screw and the gear. US Navy
  5. 5 The same manual adds that physicists recognise only two basic principles in machines: the lever and the inclined plane. US Navy
  6. 6 In that view the wedge and the screw both work on the principle of the inclined plane. US Navy
  7. 7 Science Trek, from Idaho Public Television, gives the familiar six: lever, wheel and axle, inclined plane, wedge, pulley and screw. Science Trek
  8. 8 The word “machine” comes from a Greek word meaning “to help make things easier”. OpenStax
  9. 9 Simple machines can be combined into compound machines, and many everyday tools are compound machines. Science Trek
  10. 10 The six simple machines were classified during the Renaissance. Ohio Univ.
  11. 11 Mechanical advantage is how many times a machine multiplies the force you put in: the output force divided by the input force. OpenStax
  12. 12 The theoretical mechanical advantage assumes no friction; in practice friction makes the actual mechanical advantage smaller. Britannica
  13. 13 Machines multiply force at the expense of distance: you push with less force, but over a longer distance. OpenStax
  14. 14 A machine cannot do more work than the energy put into it, so energy is still conserved. OpenStax
  15. 15 A US Navy manual puts it this way: a machine lets you gain force, but only at the expense of speed. US Navy
  16. 16 In physics, work is force multiplied by the distance moved in the direction of the force: W = fd. Britannica
  17. 17 Work is measured in joules. One joule is the work done by a force of one newton moving something one metre. Britannica
  18. 18 Holding a heavy object still, however tiring, does no work in the physics sense. Britannica
  19. 19 Push on a brick wall until you sweat and, unless it moves, you have done no work; nudge a computer mouse and you have. Science Trek
  20. 20 A force of 10 newtons that moves something 3 metres does 30 joules of work. Science Trek
  21. 21 Ignoring friction, the work you put into a machine equals the work you get out. US Navy
  22. 22 A lever is a bar or board that rests on a support called a fulcrum. Britannica
  23. 23 OpenStax describes it as a rigid bar pivoted at a fixed place called the fulcrum. OpenStax
  24. 24 All early people used the lever in some form, for moving heavy stones or as digging sticks. Britannica
  25. 25 The shadoof is a long lever with a water container on the short arm and counterweights on the long arm; it is said to have been used in Egypt and India as early as 1500 BCE. Britannica
  26. 26 With a shadoof, a person could lift several times their own weight by pulling down on the long arm. Britannica
  27. 27 A balance beam for weighing, a bar pivoted at its centre, was probably used in Egypt in about 5000 BC, says Britannica. Britannica
  28. 28 If the crowbar’s long side is five times the short side, your push is multiplied five times. Britannica
  29. 29 A nutcracker is two levers joined at a pin: if the handle is three times as far from the pin as the nut, your squeeze is multiplied three times. Britannica
  30. 30 Every lever has three parts to look for: the effort (your push), the fulcrum (the pivot) and the load. BBC Bitesize
  31. 31 In a first-class lever the fulcrum is between the effort and the load, as in a seesaw or a crowbar. BBC Bitesize
  32. 32 In a second-class lever the load is between the fulcrum and the effort: wheelbarrows, nutcrackers and some bottle openers. BBC Bitesize
  33. 33 In a third-class lever the effort is between the fulcrum and the load: tweezers, tongs and fishing rods. BBC Bitesize
  34. 34 The law of the lever: weights balance at distances from the fulcrum in inverse proportion to their weights. Twice the weight balances at half the distance. Britannica
  35. 35 For any lever, the mechanical advantage equals the effort’s distance from the fulcrum divided by the load’s distance from the fulcrum. OpenStax
  36. 36 The longer the handle on a nail puller, the more force you can exert with it. OpenStax
  37. 37 In OpenStax’s worked wheelbarrow example, the load sits 7.50 cm from the wheel’s axle and your hands 1.02 m from it. OpenStax
  38. 38 A shovel is a lever with a mechanical advantage of less than one: it gives up force to gain speed and distance at the blade. OpenStax
  39. 39 A claw hammer pulling a nail is a lever: a small force on the long handle gives a big pull on the nail. US Navy
  40. 40 A pair of scissors is a double first-class lever, with the pivot screw as the fulcrum. Illinois State Univ.
  41. 41 A nutcracker is a double second-class lever. Illinois State Univ.
  42. 42 Your forearm is a third-class lever: the muscle pulls between the elbow and the hand. Illinois State Univ.
  43. 43 Levers are all around us: door handles, the claws of a hammer, crowbars, light switches, bottle openers and hinges. Science Trek
  44. 44 The closer the fulcrum is to the object being lifted, the easier it is to lift. Science Trek
  45. 45 A wheel and axle is a wheel fixed to a shaft (the axle) so that the two turn together. Britannica
  46. 46 In its earliest form, the wheel and axle was probably used for raising weights or buckets of water from wells. Britannica
  47. 47 Its mechanical advantage is the radius of the wheel divided by the radius of the axle. Britannica
  48. 48 A doorknob is a wheel and axle. Try turning the bare square shaft with your fingers once the knob is off: it is tough work. US Navy
  49. 49 The old well windlass: an 8-inch crank turning a 2-inch drum gives a theoretical mechanical advantage of 4. US Navy
  50. 50 A car’s front wheel is not a wheel-and-axle machine in this sense, because its axle does not turn with the wheel. US Navy
  51. 51 OpenStax treats a crank as a lever that can turn a full circle about its pivot; cranks are usually designed to have a large mechanical advantage. OpenStax
  52. 52 Gears are a form of the wheel and axle. Science Trek
  53. 53 Wheels and axles are wherever things turn in a circle: fans, revolving doors, merry-go-rounds, bicycles. Science Trek
  54. 54 The wheel and axle goes back to Mesopotamia in the fifth millennium BCE, according to an Ohio University history of mechanisms. Ohio Univ.
  55. 55 A pulley is a wheel that carries a rope, cord, cable, chain or belt on its rim. Pulleys with grooved rims are called sheaves. Britannica
  56. 56 Pulleys, the blocks that hold them and the rope together are called a block and tackle. Britannica
  57. 57 A single fixed pulley has a mechanical advantage of 1: it doesn’t reduce the force, it changes its direction. OpenStax
  58. 58 For a pulley system, the mechanical advantage is roughly the number of rope sections holding up the load: 2, 3, 4 and so on. OpenStax
  59. 59 Pulling down on a flagpole rope to raise the flag is a single pulley at work: down here, up there. Science Trek
  60. 60 Pulleys work window blinds, raise sails, lift cargo and cranes, and move lifts between floors. Science Trek
  61. 61 Science Trek calls the pulley a version of the wheel and axle combined with a rope or chain. Science Trek
  62. 62 Archimedes is reported to have used compound pulleys to pull a ship onto dry land. Britannica
  63. 63 The pulley goes back to Mesopotamia in the second millennium BCE, according to the Ohio University history. Ohio Univ.
  64. 64 An inclined plane is a sloping surface used to raise heavy things. A ramp is the classic example. Britannica
  65. 65 Pushing something up a slope takes less force than lifting it straight up, if you ignore friction. Britannica
  66. 66 The steeper the slope, the closer the force gets to the full weight. Britannica
  67. 67 Without friction, the push needed is the weight times the sine of the slope’s angle: F = W sin θ. Britannica
  68. 68 Ramps and switchback roads use the inclined plane: a small force acting over a long distance does a large amount of work. Britannica
  69. 69 It takes the same amount of work, but less force, to move an object up a ramp than to lift it straight up. Science Trek
  70. 70 The Navy manual’s example: rolling a 300-pound barrel up a 9-foot plank onto a 3-foot platform takes about 100 pounds of push, a mechanical advantage of 3. US Navy
  71. 71 Stairs, escalators, ladders, wheelchair ramps and even mail chutes are versions of the ramp. Science Trek
  72. 72 Ramps were probably used during the construction of the Egyptian pyramids. OpenStax
  73. 73 Cattle ramps, mountain roads and gangplanks are all inclined planes. US Navy
  74. 74 A wedge tapers to a thin edge. Push it one way and it pushes sideways. Britannica
  75. 75 Wedges split, lift and tighten, for example to fix a hammer head onto its handle. Britannica
  76. 76 Wedges were used in prehistoric times to split logs and rocks. For rocks, wooden wedges were wetted so they would swell. Britannica
  77. 77 An axe is a wedge, and so are the teeth on a saw. Britannica
  78. 78 A wedge is really two inclined planes back to back. Science Trek
  79. 79 Wedges also hold things in place: staples, drawing pins, nails, doorstops and shims. Science Trek
  80. 80 Knives, axes, needles, scissor blades and ice picks are wedges that separate. Science Trek
  81. 81 A zip uses two ancient tools, the wedge and the hook: the slide holds a set of wedges that push the teeth together or force them apart. Indiana Public Media
  82. 82 Scissors are a compound machine: the edges of the blades are wedges, joined to make a lever. Science Trek
  83. 83 In terms of how it works, a screw may be thought of as a wedge wrapped around a cylinder. Britannica
  84. 84 Cut a right-angled triangle of paper and wind it round a pencil: the sloping edge becomes a screw thread, an inclined plane wrapped round a cylinder. US Navy
  85. 85 A jack with a 24-inch handle and a ¼-inch thread pitch can, in theory, lift about 15 tons with a 50-pound push. US Navy
  86. 86 Screw jacks lose a lot to friction, on purpose: without it, the weight of the load would spin the jack straight back down. US Navy
  87. 87 Screws are in jar lids, drills, bolts, light bulbs, taps, bottle caps and ball-point pens, and a spiral staircase is a kind of screw. Science Trek
  88. 88 A screw pump turns a big screw shape in water to lift the water up the shaft, often for farms and irrigation. Science Trek
  89. 89 Archytas of Tarentum, in the 5th century BC, is the alleged inventor of the screw. Britannica
  90. 90 The water screw is usually credited to Archimedes, but there is evidence of a similar device in Egypt earlier. Britannica
  91. 91 The screw press was probably invented in Greece in the 1st or 2nd century BC. Britannica
  92. 92 The same history traces the screw to Mesopotamia in the first millennium BCE. Ohio Univ.
  93. 93 Archimedes was born in about 287 BCE in Syracuse, Sicily, and died there in 212 or 211 BCE. Britannica
  94. 94 Britannica calls the story that he said “Give me a place to stand and I will move the Earth” apocryphal: not reliably recorded. Britannica
  95. 95 The oldest version is in Plutarch (about AD 45–120), writing some 300 years later: if there were another earth, Archimedes said, by going into it he could move this one. Rorres, NYU
  96. 96 The famous wording, “Give me a place to stand and with a lever I will move the whole world”, is from John Tzetzes, writing in the 12th century AD. Rorres, NYU
  97. 97 Plutarch also tells how Archimedes, holding the end of a pulley system in his hand, drew a loaded ship towards him in a straight line. MacTutor
  98. 98 The basic law of the lever was probably known to scholars before Archimedes; he gave it a mathematical proof. Britannica
  99. 99 The later writer Pappus mentions a treatise by Archimedes On balances and levers, which is lost. MacTutor
  100. 100 Archimedes studied three machines: the lever, the pulley and the screw. Acta Baltica
  101. 101 The Greek engineer Hero of Alexandria described five simple machines: the lever, the pulley, the wheel, the wedge and the screw. Univ. of Oklahoma
  102. 102 Another history lists Hero’s five as the winch, lever, pulley, wedge and screw. Acta Baltica
  103. 103 The ancient Greeks’ understanding of simple machines was limited to statics, forces in balance, and did not include the idea of work. Ohio Univ.
  104. 104 In 1577 Guidobaldo del Monte showed that all five of Hero’s machines could be worked out from the principle of the lever. Univ. of Oklahoma
  105. 105 Galileo, in Le Mecaniche, added the inclined plane, so the number of simple machines became six. Acta Baltica
  106. 106 In 1586 the Flemish mathematician Simon Stevin worked out the mechanical advantage of the inclined plane. Ohio Univ.
  107. 107 Stevin (1548–1620) published his triangle of forces in De Beghinselen der Weeghconst (1586), the start of a new kind of statics. Britannica
  108. 108 In Le Meccaniche, around 1600, Galileo was the first to show that simple machines do not create energy, only transform it. Ohio Univ.
  109. 109 Guidobaldo del Monte was one of Galileo’s patrons; Galileo taught at Padua from 1592 to 1610. Britannica
  110. 110 The lever goes back to the Near East in the fifth millennium BCE, according to the Ohio University history. Ohio Univ.
  111. 111 The same history calls the wedge ancient (think stone hand axes) and the ramp prehistoric, used to move heavy masses. Ohio Univ.
  112. 112 It credits Archimedes, in the third century BCE, with first developing the idea of mechanical advantage. Ohio Univ.
  113. 113 Machines do not cheat physics: they multiply force but cannot do more work than you put in. OpenStax