| A | B |
|---|
| work | the transfer of energy that occurs when a force makes an object move |
| power | the amount of work done in one second |
| joules | what work is measured in |
| work equation | applied force x distance |
| newtons | what force is measured in |
| meters | what distance is measured in |
| watts | what power is measured in |
| power equation | work divided by time |
| power equation for energy transfer | energy transferred divided by time |
| seconds | what time is measured in |
| machine | a device that makes doing work easier |
| input force | the force that is applied to the machine |
| output force | the force applied by the machine |
| mechanical advantage | the ratio of the output force to the input force |
| mechanical advantage equation | output force divided by input force |
| efficiency | a measure of how much of the work put into a machine is changed into useful output work by the machine |
| efficiency equation | output work divided by input work times 100% |
| simple machine | a machine that does work with only one movement of the machine |
| lever | a bar that is free to pivot or turn around a fixed point |
| a first-class lever | using a screwdriver to open a paint can |
| a second-class lever | a wheelbarrow |
| a third-class lever | a baseball bat |
| ideal mechanical advantage of a lever equation | length of input arm divided by length of output arm |
| pulley | a grooved wheel with a rope, chain, or cable running along the |
| fixed pulley | an example such as a cable attached to an elevator |
| movable pulley | an example such as a block and tackle help to reduce the force needed to move a weight |
| wheel and axle | a simpler machine consisting of a shaft or axle attached to the center of a large wheel, so wheel and axle rotate together |
| ideal mechanical advantage of wheel and axle | radius of the wheel in meters divided by the radius of the axle in meters |
| inclined plane | a sloping surface that reduces the amount of force required to do work |
| ideal mechanical advantage of an inclined plane | length of slope in meters divided by height of slope in meters |
| screw | an inclined plane wrapped in a spiral around a cylindrical post |
| wedge | an inclined plane with one or two sloping sides |
| compound machine | two or more simple machines that operate together |
