1. Chapter 5: Work and Machines

2.  Describe the six types of simple machines.  Explain how the different types of simple machines make work easier.  Calculate mechanical advantage.

3.  Simple Machine: a machine that does work with only one movement of the machine.

4.  Lever: a rigid bar that rotates around a fixed point called the fulcrum.  The bar may be either independent or attached to another object.

5.  In use, a lever has both an input force and an output force.

6. Input Force Output Force

7.  First Class Lever: fulcrum is in the middle of the input and output forces  MA may be greater or less than 1  Ex: scissors, see-saw, crowbar

8. Input Force Output Force

9.  Second Class Lever: output force is in-between the input force and the fulcrum.  MA is always greater than 1  Ex: wheelbarrow, nut cracker, bottle opener

10. Input Force Output Force

11.  Third Class Lever: input force is in-between the output force and the fulcrum.  MA is always less than 1  Ex: tweezers, staple remover, broom

12.  Pulley: a machine that consists of a wheel that turns freely in a frame called a block.

13.  A pulley can be used to change the direction of a force or to increase input force depending on how the pulley is arranged.

14.  Fixed Pulley: changes the direction of a force; however it does not create a mechanical advantage.  Example: Elevator

15.  A single moveable pulley creates a mechanical advantage; however it does not change the direction of a force.

16.  The mechanical advantage of a moveable pulley is equal to the ropes that support the moveable pulley.

18.  Wheel and Axle: a simple machine consisting of a larger wheel rigidly secured to a smaller wheel or shaft, called an axle.

19.  When either the wheel or axle turns, the other rotates with it.  One full revolution of either part causes one full revolution of the other part.

21.  Examples:  Pencil sharpener  Door knob  Faucet handles

22.  Inclined plane: is a sloping surface that reduces the amount of force required to do work by increasing the distance over which work is done.  The inclined plane makes it easier to move a weight from a low height to a high height.

24.  Wedge: an inclined plane that has one or two sloping sides.  It changes the direction of the input force.

25.  Examples:  Knife/ax  Door stopper

26.  Screw: an inclined plane wrapped in a spiral around a post.  The threads form a tiny ramp that run upward from its end.

27.  Example:  Many types of lids  Screws

28.  Two or more simple machines operating together.