Question

the work input always equals the work output in an ideal machine and the input will exceed the output in real machines because of _____.
a friction
b slope
c distance
d energy conservation

Explanation:

In real machines, friction exists and causes energy (in the form of work) to be lost as heat, sound, etc. So work input exceeds output. Slope relates to inclined planes' mechanical advantage, distance is part of work formula (\(W = Fd\)) but not the reason for input > output here, and energy conservation is a principle (ideal machines follow it, real ones still conserve energy but some is lost to friction, so friction is the cause).

Answer:

a. friction