This may be demonstrated with a ten pound plate, string, and a towel. Friction can be useful, for example people used it to make fires. Too much friction makes heavy objects hard to move. This can be done using chains or sand they make the touching surfaces more rough. The round wheel was one of the first human inventions because it made things easier to move.
Wheels reduce friction because only a little part of it touches the ground at one time.
Other round objects help reduce friction too. Ball Bearings are smooth balls made of metal. Placed next to each other they can roll very easily . The efficiency of a machine depends on how much work we get out of it. Some of the energy we put into a machine is lost to friction.