What are the disadvantages of friction?

what are the disadvantages of friction? what is the principle of ball bearings?

  1. The main disadvantage of friction is that it produces heat in various parts of machines. In this way some useful energy is wasted as heat energy.
    Due to friction we have to exert more power in machines.
  2. It opposes the motion.
  3. Due to friction, noise is also produced in machines.energyis wasted in sound energy.
  4. Due to friction, engines of automobiles consume more fuel which is a money loss.
  5. Machine efficency is decreased: energy input is lost to heat and many moreā€¦