2.1

• mechanical advantage

  • The amount by which a machine can multiply force (or make things easier)
• input force - the force applied to the machine
• output force - the force the machine applies to the object
• force is measured in newtons

  MA = output force / input force
• speed ratio - A measure of how the speed of the object is affected by a machine

  SR = input distance / output distance
• mechanical advantage less than one - speed advantage

  mechanical advantage more than one - force advantage
• friction - a force that opposes motion

  • Caused by surface roughness of materials, extra force is needed to overcome fricton
• affects of friction

  • Mechanical Advantage is affected by friction, but Speed Ratio is not
  • The distance is not changed by friction, just the effort to move an object
• efficiency - The measurement of how well a machine or device uses energy

  • Any machine (ex. Pulley) will lose some energy
  • Usually the energy lost is due to friction
  • “lost” because it is not being used directly for the pulley’s task of lifting

  ~The more energy lost, the less efficient the machine~