AFOQT mech

  1. Force
    something that can change the velocity of an object
  2. friction
    alway acts in the opposite reaction as to retard relative motion
  3. sliding friction
    when two objects are in close contact
  4. spring scale
    measures friction
  5. newton
    is a unti of force which is 4.45N=1lb
  6. equilibruim
    when an object is at equilibrium all forces acting on it are equal to zero
  7. friction coefficient
    depends more on the pressure between two surfaces rather than velocity
  8. viscious drag
    when a solid mass passes thru a liquid, gas or air vicous drag will occur. Viscous drag will increase as speed increases. 

    • - aerodynamic shapes come in to play
    • -properties of the fluid also come into play
  9. Weight
    weight is equal to MG; mass x gravity
  10. elastic recoil
    when you applhy pressure on a solid object, that object will bend but also push back with a force equal to one exerted on it.
  11. tension
    tension can be measured by cutting a rope and introducing a spring scale
  12. buoyancy
    buoyancy acts in an upward direction on anything submerged in a liquid or gas.
  13. Sinking
    An object with a weight greater than the booyancy of the fluid it is in will sink.
  14. forces
    forces exist only in pairs
  15. there are six simple machines
    • these are 
    • 1. lever
    • 2. incline plane
    • 3. pulley
    • 4. wedge
    • 5. wheel and axle
    • 6. screw
  16. Work
    work is the force applied over a distance
  17. Mechanical Advantage
    Output ratio to inout ratio of work produced by a machine
  18. Work 
    whenever a force moves something over a distance. W=FxD
  19. Newton
    Force required to move 1 kilogram one meter in one second.

    1kg x m/s
  20. Mecahnical Advantage Formula
    MA = Fl/Fe = load/effort
  21. TCos theta
    the force that actually produces horizontal movement when a force is appled at an angle.
  22. Machine Efficiency
    ME= Wout/Win = work put out / work put in
  23. Vector
    a Force with both magnitude and direction
  24. Lever
    FeDe = FlDl 

    • MA= Fl/Dl
    • MA = Re/Rl
  25. Lever types
    • there are 3 types. 
    • class 1- fulcrum between effort and load; dolly

    class 2- Fulcrum on one end, with load between; wheel barrow, nutcracker

    class 3- Effort in the middle of load and fulcrum; fisherman, tongs
  26. Incline Plane
    plane set at and angle

    MA = lenght / height

    • Woutput = load x height
    • Win= Force x lenght of ramp
  27. Wedge
    A double inclined plane that moves to exert a force along the lenght of its sides to push two objects apart

    -knife, ax, chisel
  28. Wheel and Axle
    wheel and axle
  29. Screw
    can be thought of as an inclined plane with a wedge wrapped around a cylinder. 

    forces are applied perpendicular to the groove
  30. Pulley
    the pulley uses the principle of applying force over a longer distance. It also uses tension in the rope or cable. 
  31. MA of Pulley
    De = Dl x supporting strands

    E = Load / number of strands

    W = F x D
  32. Hydraulic Jacks
    liquids are nearly incompressible. 

    MA = Al / Ae

    Aii / Ai = Di / Dii 

    • Aii = diameter of larger circle
    • Ai = smaller
    • Di= Vertical distance of smaller
    • Dii=Larger one
  33. Gears
    MA = # of teeth in load gear / # of teeth in effort gear
  34. Power
    • 1 ft-lb/s = 550 hp
    • 746 joules = 1 hp
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AFOQT mech