Bell Work: Simple machines1. Simple machines make work ( easier / harder ).

Match the tool to the type:

Type of machine Tool

2. Incline plane Door knob

3. Wheel and axel Flag pole

4. Lever Ramp

5. Pulley Crow bar

Machines

Machines A machine is a device that makes work

easier. Examples: hammer, bicycle ramp, scissors,

shovel, and doorknob

Machines Machines can do a variety of jobs: pump

water from a well, hoist a sail, plow a field, catch a fish.

Machines make work easier by changing the size or direction of the applied force.

Two forces involved in using a machine

1. The force applied to a machine is the effort force (Fin)

Example: when you pull down on the handle of a crowbar, you are applying an effort force.

Two forces…2. The force applied by the machine is the

resistance force (Fout) Example: Motor turns fan

Work Input

Output

What do machines do?? Machines make work easier, but do not

multiply work. So, work output can never be greater than

work input

Mechanical Advantage

Ideal Mechanical Advantage

Efficiency

Types of Simple MachinesI. Inclined Plane – a slanted surface used to

raise an object. Example: a ramp Wedges and Screws – wedge is an inclined

plane that moves. Have an edge that is thinner at one end. Examples: knife, ax, wedge

A screw is also an inclined plane. It is an inclined plane wrapped around a cylinder to form a spiral.

Simple MachinesII. Levers – a bar that is free to pivot a fixed

point when an effort force is applied. The fixed point of the pivot is called the fulcrum.

Levers****Three classes of levers:

1. Fulcrum is between the effort force and the resistance force. Example: crowbar, pliers, scissors and seesaws

Resistance force is between fulcrum and effort force. Examples: wheelbarrows, doors

Effort force is greater than the resistance force and the fulcrum

Simple machinesIII. Pulleys – a chain, belt, or rope wrapped

around a wheel. A pulley can change either the direction or the amount of an effort force.

IV. Wheel and Axle – a lever that rotates in a circle. Made of 2 wheels of different sizes. Examples: bicycles, Ferris wheels, water wheels and gears.