​Efficiency and Friction

• ​Mechanical Efficiency measures how well a machine converts input work into output work

• ​Ideally, we want the machine to work at 100% efficiency, but that's not always the case! Heat may be lost (or too much gained) due to friction

• ​Friction is the force that holds back the motion of sliding objects (think about trying to slide around a wooden floor with shoes on!).

• ​Friction reduces a machine's efficiency

  • ​Reducing friction can help a machine run more efficiently

    • ​We can do this by making the surface smoother or by lubricating the surface

​Efficiency

​Ways to increase the efficiency of a lever are:

1. Use a sharp-pointed fulcrum (triangle) rather than a rounded fulcrum (rock)

2. Replace the fulcrum with an oiled hinge (like on a door)

3. Use a more rigid bar

4. Use a shorter bar

Ways to increase the efficiency of a pulley are:

1. Use a grooved wheel

2. Lubricate (oil) the axle of the grooved wheel

3. Use a cable or rope that grips the grooved wheel (does not slip)

Ways to increase the efficiency of an inclined plane are:

1. Use a smoother surface on the ramp

2. Lubricate (oil) the surface of the ramp

3. Use a shorter ramp