Machine
A
machine is any
mechanical or
organic device that transmits or modifies
energy to perform or assist in the performance of tasks. It normally requires some energy source ("input") and accomplishes some sort of
work.
People have used mechanisms and machines to amplify their abilities since before written records were available. Generally these devices decrease the amount of
force required to do a given amount of work, alter the direction of the force, or transform one form of
motion or energy into another.
The
mechanical advantage of a
simple machine is the
ratio between the force it exerts on the load and the input force applied. This does not entirely describe the machine's performance, as force is required to overcome
friction as well. The
mechanical efficiency of a machine is the ratio of the
actual mechanical advantage (AMA) to the
ideal mechanical advantage (IMA). Functioning physical machines are always less than 100% efficient.
Modern power
tools,
automated machine tools, and human-operated power machinery complicate the definition of "machine" greatly. Machines used to transform
heat or other energy into mechanical energy are known as
engines.
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