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65 Cards in this Set

  • Front
  • Back
product of force and distance
work
for a force to do work on an object, some of the force must act in the ____ -_____ as the object moves
same direction
no movement equals
no work
any part of a force that does not act in the same ____ of motion does ___ work on an object
direction, no
SI unit for work
joule
rate at doing work
power
doing work at a faster rate requires
more power
to increase the power you increase
the amount of work done in a given time or you can do a given amount of work in less time
formula for power
power equals work/time force* distance/ time
SI unit for power
watt
746 watts
1 horsepower
device that changes a force
machine
machines make work
easier to do
machines change
size of a force needed, the direction of a force or the distance over which a force acts
if you increase the distance you
increase the force
device that changes a force
machine
machines make work
easier
machines change_____
size of a force needed, direction of a force or the distance over which a force acts
some machines ____ the applie force but ____ the distance over which the force is exerted
decrease/ increase
because of ___ the work done by a machine is always ___ than the work done on the machine
friction/ less
force you exert on a machine
input force
distance the input force acts through
input distance
force exerted by the machine
output force
distance the output force is exerted
output distance
(output force)( output distane)
work output
number of times that the machine increases an input force
mechanical advantage
equals the ratio of the output force to the input

AMA= output force/ input force
actual mechanical advantage
mechanical advantage in the absense of friction
ideal mechanical advantage
because friction is always present, the __ ____ ____ of a machine is always less than the ideal
sctual mechanical advantage
formula for ideal mechanical advantage
ideal= input distance/ output distance
percentage of the work input that becomes work output
effiency
because there is always some friction the ___ of any machine is always less than 100%
effiency
six types of simple machines
lever, wheel & axle, inclined plane, wedge, screw, pulley
rigid bar that is free to move around a fixed point
lever
fixed point the bar rotates around
fulcrum
levers are classified into 3 categories based on
the locations of the input force, output force adn the fulcrum
distance between the input force and the fulcrum
input arm
distance between the output force and the fulcrum
output arm
to calculate the ideal mechanical advantage of any lever
IMA=input arm/output arm
fulcrum is always located between the input force and the output force
1st class lever
output force is located between the input force and the fulcrum
2nd class lever
input force is located between the fulcrum and the output force
3rd class lever
mechanical advantage can be greater than 1, equal to 1 or less than 1
1st class lever
mechanical advantage is always greater than 1
2nd class lever
mechanical advantage is always less than 1
3rd class lever
simple machine that consists of two disk/cylinders, each one with a different radius
wheel and axle
to calculate the ideal mechanical advantage of the wheel adn axle_____
radius where the input force is exerted/ radius where the output force is exerted
slanted surface along which a force moves an object to a different elevation
inclined plane
the ideal mechanical advantage of an inclined plane is the distance along the ______
incline plane/ its change in height
v-shaped object whose sides are two inclined planes sloped toward eachother
wedge
a thin wedge of a given length has a ___ IMA than a think wedge of the same length
greater
inclined plane wrapped around a cylinder
screw
screws with threads that are closer together have a ____ IMA
greater
simple machine that consists of a rope that fits into a groove in a wheel
pulley
the ideal mechanical advantage of a pulley/pulley system is equal to
the number of rope sections
wheel attached in a fixed location,
fixed pulley
attached to the object being moved
movable pulley
combined fixed and movable pulleys
pulley system
combination of two or more simple machines that operate together
compound machine
example of a compound machine
watch
reason james watt named the horsepower
because horses were the most commonly used power in the 1700s
output work is always ____ than the input work
less
materials engineers use to increase the mechanical advantage of a machine
low-friction materials and lubricants
screwdriver used to pry the lid off a paint can is an example of a
1st class lever
you pull easier if you have more
MECHANICAL ADVANTAGE