Explain why the output work for any machine can't be greater than the input work.

Work is energy.  Energy can't be created or destroyed.  Wherever you see
energy appearing, it must have come from somewhere.  If you see 10 units
of energy go INto a machine and 11 units of energy come out, then 1 unit
must have been created inside the machine.  But that's not possible.

1) when you rub your hands together quickly, the kinetic energy is converted to mechanical energy.2) thermal energy from the sun travels to earth as infrared waves.3) energy is transferred through the matter of space by electromagnetic waves. 4) when a match is burned, chemical potential energy is converted to thermal and radiant energy. 5) seismicwaves are caused by back and forth movement , or vibration, of an object. 6) mechanicalenergy in an engine changes thermal energy into kinetic energy to make a car move.