| A | B |
|---|
| machine | device that makes work easier |
| wheel and axle | two different sized wheels that turn together around the same point |
| effort force | force applied to a machine |
| resistance force | force that opposes the effort force |
| mechanical advantage | number of times a machine multiples the effort force |
| ideal mechanical advantage | mechanical advantage a machine would have with no friction |
| What are the six simple machines? | lever, inclined plane, wheel and axle, pulley, screw, wedge |
| work output | work done by a machine |
| work input | work done on a machine |
| efficiency | ratio of work output to work input |
| work output= | resistance force x resistance distance |
| work input = | effort force x resistance force |
| percentage efficiency = | work output / work input x 100 |
| lever | bar that is free to turn around a fixed point |
| fulcrum | fixed point around which a lever pivots or turns |
| How does a lever make work easier? | A lever can increase the force, change the direction of a force, and the distance over which a force acts |
| effort arm | is the distance rom the effort force to the fulcrum |
| resistance arm | is the distance from the resistance force to the fulcrum |
| IMA of a lever = | effort arm length / resistance arm length |
| How many classes of levers are there? | There are 3 classes of levers |
| first-class lever | the fulcrum is between the effort force and the resistance force. These levers multiply the force and change the direction of the force. |
| second-class lever | has the resistance between the effort force and the fulcrum. They multiply force, but the direction of the effort force is not changed |
| third-class lever | the effort force is between thefulcrum and the resistance force . These levers multiply the distance the resistance force moves, but the direction is not changed |
| Pulley | rope wrapped around a wheel |
| What does a pulley change? | the direction of a force, the size of the force |
| What does a fixed pulley change? | the direction of the effort force, they do not increase the effort force |
| What is a fixed pulley? | A fixed pulley is attached to something that does not move |
| What is a movable pulley? | a movable pulley can move as the rope is pulled through it |
| What does a movable pulley change?e | It increases or multiplies the size of the effort force |
| What is the IMA of a single movable pulley equal to ? | the number of supporting rope segments thatlift the resistance |
| What is a pulley system? | A pulley system is made up of both fixed and movable pulleys |
| inclined plane | slanted surface or ramp |
| inclined | slanted |
| How does an inclined plane make work easier? | by changing the angle at which you have to exert force to lift resistance |
| IMA of an inclined plane= | length /height |
| wedge | made of two inclined planes back to back |
| screw | an inclined plane wrapped around a cylinder |
| compound machine | machine that combines two simple machines or more |
| The MA of a compound machine = | the product (multiply) all the simple machines that make it up |
| Scissors | two levers joined by a screw |
| bicycle | wheels and pedals are wheels and axles, pedals are attached to levers, brakes, hnadlebars, and gearshift controls are levers chains are pulleys and screws hold it together |
| agricultural socities ( farming) | used machines to water their crops, crush grain into flour, and cut wood to build homes |
| Industrial Revolution | many machines were invented as the steam engine, telegraph, telephone. Steam began to replace animals as a source of energy |
| Modern machines | fossil fuels and nuclear energy are used to operate these machines |
