Which increases the work output of a machine?
a. increasing friction
b. reducing friction
c. reducing input distance
d. increasing output distance

D. Increasing output distance

Explanation:

The work done for any machine is given by:  

Output work done of machine = W = Fd

Where,

F = output force  

d = output distance  

Output work of machine can only be increased by increasing output force or output distance. Hence, in the current situation output work of machine can be increased by increasing output distance.

d) physical means can be used to separate the components of air.