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chapter 8 word$
| Question | Answer |
|---|---|
| Work | occurs when a force causes an object to move in the direction of the force |
| Work is ONLY done when | a force makes that object move |
| These 2 things must be present in order for work to be occurring | object moves as the force is applied, and the direction of the objects motion is the same as the direction of the force applied |
| What is the work formula | work equals force times distance |
| Power | the rate at which work is done |
| What is the power formula | power equals work done/time |
| Watt | expressed in joules per second called watts |
| Work Input | the work you do on a machine |
| Work Output | the work done by the machine |
| When can work output be GREATER than work input | NEVER |
| “Machines don’t save work”. True or false? Explain your answer | they don’t they just decrease the amount of input force needed |
| Mechanical Advantage | tells you how many times the machine multiplies force |
| Mechanical Advantage formula | output force/input force |
| What are the 6 simple machines | lever, inclined planes, wedges, wheel, pulley, screws |
| Lever | consist of a bar that pivots from a fixed point, called a fulcrum |
| Examples of lever | hammer, seesaw |
| Fulcrum | the fixed point used by levers |
| Examples of each of the 3 classes of levers | seesaw, bottle cap opener, barbells |
| Inclined Plane | a straight slanted surface |
| How do you increase the mechanical advantage of an inclined plane | making it longer |
| Examples of Inclined Planes | ramps for bikes or skateboards |
| Wedge | a double inclined plane that moves |
| Examples of Wedges | a knife |
| Screws | inclined plane wrapped in a spiral |
| Examples Screws | a screw |
| How do you change the mechanical advantage of a screw | the longer the spiral |
| Wheel & Axle | two circular objects of different sizes |
| Examples of Wheel & Axle | doorknob |
| Pulley | grooved wheels that holds a rope or cable |
| Examples of Pulleys | cranes |