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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 |