An ideal machine is a machine that cannot exist in reality for a number of reasons:

1. It is frictionless.
2. Its actual mechanical advantage is equal to its ideal mechanical advantage.
3. Its mechanical efficiency is 100%.

there actually IS an ideal machine out there.. but do u know what it is? find out and add to this! In physics, friction is the non-conservative resistive force that occurs when two surfaces travel along each other when forced together. ... In physics, the actual mechanical advantage (abbreviated AMA) is the mechanical advantage of a real machine. ... In physics, the ideal mechanical advantage (abbreviated IMA) is the mechanical advantage of an ideal machine. ... In physics, mechanical efficiency is the effectiveness of a simple machine. ... A percentage is a way of expressing a proportion, a ratio or a fraction as a whole number, by using 100 as the denominator. ...