Work
transfer of energy that occurs
when a force makes an object
move; measured in joules.
Power
amount of work done, or the
amount of energy transferred,
in a certain amount of time;
measured in watts.
Machine
device that makes doing work easier by
increasing the force applied to an object, by
changing the direction of an applied force, or
by increasing the distance over which a force
can be applied.
Effort force
force exerted on a
machine that is used
to do work.
Resistance
force
force applied by a
machine to overcome
resistance.
Mechanical
advantage
number of times a
machine multiplies the
effort force applied to it.
Efficiency
measure of how much of the
work put into a machine is
changed into work done by a
machine.
Simple
machine
machine that does work with only one
movement; includes the lever, pulley,
wheel and axle, inclined plane, screw,
and wedge.
Lever
simple machine made
from a bar that is free to
pivot about a fixed point.
Pulley
simple machine that consists of a
grooved wheel with a rope, chain, or
cable that runs along a groove,
changes the direction of the effort
force, and can be fixed or movable.
Wheel and
axle
simple machine that consists
of two different-sized wheels
that rotate together.
Inclined plane
simple machine that consists of a sloping
surface, such as a ramp, that reduces the
amount of force needed to lift something by
increasing the distance over which the force
is applied.
Screw
simple machine that consists
of an inclined plane wrapped
in a spiral around a cylindrical
post.
Wedge
simple machine that consists
of an inclined plane with one
or two sloping sides.
Compound
machine
combination of two or
more simple
machines