E ground pushes you forward. But that interaction is friction. Reduce friction and it doesn't matter how strong your legs are, the surface is incapable of pushing you accordingly. The coefficient of static friction is very low so it is easy to slide your foot rather than push.
The fusion on water is an enxothermic change but at this temp, the temp-entropy product is outweighed by the change in enthalpy.
All are the same. It equals to the same thing.
It takes into account the different molecular masses of the different chemicals by providing a fixed and standardised number of molecules/ atoms for chemicals to be measured
