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Work & Simple Machines

Work & Simple Machines. Define WORK. Work is done when a FORCE causes an object to MOVE. This type of simple machine is a rigid bar that pivots around a fixed point. A LEVER is a rigid bar that pivots around a fixed point. How much work is done when a 150N rock is pushed 10meters?. W= F x D

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Work & Simple Machines

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  1. Work & Simple Machines

  2. Define WORK. Work is done when a FORCE causes an object to MOVE

  3. This type of simple machine is a rigid bar that pivots around a fixed point. A LEVER is a rigid bar that pivots around a fixed point

  4. How much work is done when a 150N rock is pushed 10meters? W= F x D W = 150N x 10m W = 1,500 J

  5. What is the Ideal Mechanical Advantage to the movable pulley below? The IMA is equal to the number of ropes supporting the weight. Because you are pulling UP, there are TWO ropes supporting the box. The IMA = 2

  6. 780 J of work was done to move a couch 3 meters. How much force was applied? F = W ÷ D F= 780 J ÷ 3 m F = 260 N

  7. What are TWO of the three ways that machines make work easier? • Change direction • Change distance • Change the amount of input force

  8. input What is the “Input Force” Input force is the force that YOU apply to the machine

  9. Define MECHANICAL ADVANTAGE Mechanical advantage is how much the input force is multiplied by the machine

  10. This type of Simple Machine is an inclined plane that can move A WEDGE is an inclined plane that moves

  11. r = 12cm r = 36cm The Ideal Mechanical Advantage of a Wheel and Axle is the Radius of the Wheel ÷ Radius of the Axle. What is the IMA of the wheel and axle below? The IMA = 36 ÷ 12 IMA = 3

  12. output What is the “Output Force” The output force is the force that the machine does

  13. output In put MA If the mechanical advantage of a machine is 3, how much force do you need to apply to lift 78 N? Input Force = Output ÷ MA Input force = 78N ÷ 3 Input force = 26N

  14. What is the Ideal Mechanical Advantage to the pulley system below? The IMA is equal to the number of ropes supporting the weight. Because you are pulling UP, there are THREE ropes supporting the box. The IMA = 3

  15. What is the efficiency of a machine that does 325 J of work, when 450 J of work is put into the machine? Efficiency = output work ÷ input work x 100 Efficiency = 325 J ÷ 450 J x 100% Efficiency = 72.2%

  16. This simple machine is made up of two or more simple machines. A COMPOUND MACHINE is made up of two or more simple machines working together.

  17. What is the Mechanical Advantage of a machine if you put in 10N of force and the machine puts out 120N of force? MA = output force ÷ input force MA = Output force ÷ Input force MA = 120N ÷ 10N MA = 12

  18. What is the formula for WORK? Work = Force x Distance

  19. What is the Ideal Mechanical Advantage to the fixed pulley below? The IMA is equal to the number of ropes supporting the weight. Because you are pulling down, there is only ONE rope supporting the box. The IMA = 1

  20. Why can’t machines be 100% efficient? Machines are not 100% efficient because of FRICTION!

  21. fulcrum The pivot point of a lever is called a … The FULCRUM is the pivot point.

  22. Output Work In put Work Eff. A machine has 68% efficiency. If you put in 59 J of work, how much work will the machine do? Output work = Eff. x Input Work Output work = 0.68 x 59 J Output work = 40.1 J

  23. This type of Simple Machine has a flat slanted surface that increases the distance over which a force is applied. An INCLINED PLANE

  24. What is the UNIT used for WORK? Work is = Nm or Joule (J)

  25. The Ideal Mechanical Advantage of an Inclined Plane is Length of ramp ÷ Height of ramp What is the IMA of the ramp below? 50 m 10 m IMA = Length ÷ Height IMA = 50 ÷ 10 IMA = 5

  26. An inclined plane wrapped around a cylinder is a _________ A SCREW is an inclined plane wrapped around a cylinder.

  27. 5 m fulcrum 2.5 m The Ideal Mechanical Advantage of a lever is Distance from fulcrum to input force ÷ Distance from fulcrum to output force. What is the IMA for the lever below IMA = 5 ÷ 2.5 IMA = 2

  28. Circ. = 8 cm Pitch = 2cm The Ideal Mechanical Advantage of a screw is the circumference of the screw ÷ the pitch. What is the IMA of the screw below? IMA = 8 ÷ 2 IMA = 4

  29. This simple machine is made up of two circular objects that are fastened together and rotate on a common axis. A WHEEL and AXLE.

  30. What is the Ideal Mechanical Advantage to the pulley system below? The IMA is equal to the number of ropes supporting the weight. Because you are pulling down, there are only TWO ropes supporting the box. The IMA = 2

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