Simple Machines LeversPulleys Inclined Plane

Simple Machines Can multiply or change the direction of an applied force.

Simple Machines Machines do not multiply work - they only make the act of doing work more convenient.

Simple Machines How do machines make doing work easier? Changing the direction of input force Multiplying input force

Simple Machines Terminology You exert the effort force on the machine The machine exerts a resistance force on the object it is moving

Simple Machines Terminology The mechanical advantage of a machine tells you by what factor your effort force has been changed.

Simple Machines MA = F r / F e F r = Resistance Force F r = Resistance Force F e = Effort Force Also called the actual MA or AMA.

Simple Machines The ideal mechanical advantage of a machine is the ratio of how far the effort force moved divided by how far the resistance force moved.

Simple Machines IMA = d e / d r d r = Resistance Distance d r = Resistance Distance d e = Effort Distance

Simple Machines The AMA will always be less than IMA because some of your effort force- generated energy will be lost in the workings of the machine. (Friction!!!)

Simple Machines Efficiency = AMA / IMA x 100% = Work output/Work input = W out / W in = (F r d r / F e d e ) x 100%

Levers A lever is a fixed rod that has a moveable pivot point of fulcrum. Depending on the position of the fulcrum, the lever can produce a force or a distance advantage.

1 st Class Levers When the fulcrum is not at either end, the lever is called 1 st class. This kind of lever always changes the direction of the force.

1 st Class Levers If the fulcrum near the resistance, there is a force advantage. A small effort force can move a larger resistance force. FrFrFrFr FeFeFeFe

1 st Class Levers If the fulcrum near the effort, there is a distance advantage. A small effort distance can move a larger resistance distance. FrFrFrFr FeFeFeFe

2 nd Class Levers When the resistance is not at either end, the lever is called 2 nd class. This kind of lever always a force advantage. FrFrFrFr FeFeFeFe

3 rd Class Levers When the effort is not at either end, the lever is called 3 rd class. This kind of lever always a distance advantage. FrFrFrFr FeFeFeFe

Pulleys A pulley is a lever incorporated into a wheel. Pulleys require a cable to connect the effort to the resistance. FrFrFrFr FeFeFeFe As the effort force is pulled down with the help of gravity… … the resistance force is pulled up an equal distance.

Pulleys Sometimes the resistance attaches to the axle of the pulley to create a moveable pulley. FrFrFrFr FeFeFeFe As the effort force is pulled up… … the resistance force moves up with the pulley.

Inclined Plane An inclined plane is a ramp that allows a weight to be raised without being lifted vertically. It can also be used as a wedge.

Inclined Plane The effort force to pull up the ramp is always less than the weight. Ramps give a force advantage. FrFrFrFr FeFeFeFe

What kind of Simple Machine? 1 st class lever 2nd class lever 3rd class lever

What kind of Simple Machine? This is an advertisement for the Honda Accord that uses a variety of simple machines. How many do you recognize? Movie