Science Forces & Work / Simple Machines
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to be considered work, you need a ____ ____ through which a force acts
force and distance
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formula for work
work=force X distance
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what is the unit for work
joules
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a machine is
any device that makes doing work easier
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two basic types of SM of which all other SM are variations of
inclined planes and levers
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what do most SM do
make work easier by reducing the force needed
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do SM make less work?
no, SM make work easier they do not decrease the amount of work
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SM can actually make more work due to
friction
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"machines make work easier" force vs. distance
SM make work easier to do by decreasing the force required by increasing the distance over which the work is done
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a force applied by a machine to an object is the
resistance force
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a force applied to a machine by a person is the
effort force
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what are the exceptions to SM make work easier and an advantage of each machine
single fixed pulley- changes the direction of a force; 3rd class lever-gives us increased speed
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Is work done when someone is sitting on a cushion on the floor
no work
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a baseball is hit into the bleachers
work is done
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Mary holds a doorstop in one place to show you an example of a wedge
no work
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a little girl is pushed on a swing
work is done
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examples of inclined planes
wedge and screw
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examples of levers
pulley and wheel and axle
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an inclined plane decreases the ____ needed to lift an object by ____ the distance that force is applied
force; increasing
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less force=
more distance
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more force =
less distance
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inclined planes can increase the amount of work done due to
friction
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if the force required to lift a barrel into the back of a truck was 124 Newtonss without a SM, what would the force required to get the barrel into the back of the truck using a ramp
less than 124 Newtons
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if it takes 45343 joules of work to lift a barrel into the back of a truck without using a SM, how much work would be required to get the barrel into the back of the truck using a ramp
more than 45343 Joules