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36 Cards in this Set
- Front
- Back
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a transfer of energy that occurs when a force makes an object move
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work
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what are the two things that determine if something is work?
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object has to move
motion of object has to be in same direction of applied force |
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formula for work
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work=force x distance
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what is force measured in? force? distance?
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J,N,M
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amount of work done in a certain amount of time
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power
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formula for power
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power= work/time or energy/time
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what is power measured in?
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watts
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i kilowatt = how many watts?
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1000
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how many watts equal one hp?
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746
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a device that makes doing work easier
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machine
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how do machines make work easier?
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increases force, increases distance and changes direction of applied force
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what two forces are involved when a machine does work?
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effort and resistance
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force applied to machine
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effort force
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force applied by machine
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resistance force
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two kinds of work done when using a machine
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input and output
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work done by you on machine
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input work
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work done by the machine
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output work
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why will Wout be always less than Win?
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some of the enrgy changes to heat due to friction
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number of times a machine multipleies the effort force
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mechanical advantage
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formula for mechanical advantage
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MA= resistance force/effortforce
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when does MA = 1?
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when only direction changes
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measure of how much of the work put into a machine is changed to useful output work by the machine
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effinecny
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formula for eefficency?
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effiency=Wout/Win x 100
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efficeny of real machines is always less than what?
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100 %
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a machine that does work only with one movement
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simple machine
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six type of simple machines
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lever pulley wheel and axle inclined plane screw wedge
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bar that is free to pivot ot turn about a fixed point called fulcrum
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lever
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distance from the fulcrum to where the effor is applied is called the
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effort arm
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the distance from the fulcrum to where the resistance force is applied is called the
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resistance arm
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a fixed pulley is a modified form of a what?
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lever
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for a fixed pully, the force isnt multiplied but the ___ changes
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direction
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the force is __ for a moveable pulley
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multiplied
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modified form of wheel and axle
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gears
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for a 1st class lever the force ___and the __changes
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multiplie, direction
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what happens in a 2md class lever?
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force multiplies
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3rd lever the force doenst multiply nor does direction change, but
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increases distance over which force is applied.
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