Answer:
Some work is always lost to overcome friction The output force is always less than the input force The mechanical advantage is never exactly equal to 1 The input distance is always greater than the output distance
Step-by-step explanation:
Efficiency is the percent of work put into a machine by the user (input work) that becomes work done by the machine (output work). The output work is always less than the input work because some of the input work is used to overcome friction.