True: the ideal mechanical advantage of a machine is always greater than the actual mechanical advantage because all machines must overcome friction.
Explanation:
For a simple machine, it is possible to calculate two types of mechanical advantage:
1) The Ideal Mechanical Advantage (IMA) is given by
where
is the resistance arm
is the effort arm
The IMA gives the mechanical advantage of the machine if there are no friction forces acting on it, and if all the work in input is converted into work in output with no loss of energy
2) The Actual Mechanical Advantage (AMA) is given by
where
L is the load (the force in output)
E is the effort (the force in input)
The AMA gives the real mechanical advantage of the machine. For an ideal machine,
Because there is no loss of energy due to friction.
For a real machine instead,
because part of the input energy is converted into thermal energy and other forms of energy due to the presence of friction, so it is "wasted" energy.
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