In factories, friction between moving parts of heavy machineries is reduced by ___________.
heating machine parts
using lubricants
cooling machine parts
using sand
Friction in a moving parts of a machine can be reduced by using ___________.
Name the substance used to reduce friction between the moving parts of a machine.
Friction in parts of a machine can be reduced by using_____.
Why is lubricating oil put on the moving parts of a machine?