The average weight of an adult male is 750 newtons. In computing for weight in newtons. W = ma; where m = weight in kilograms and a = acceleration due to gravity which is equal to 9.81 m/sec2.
The kinetic energy of the shopping cart increases. This speeds up the energy rate of friction between the wheel and the floor giving off more kinetic energy so the speed rate can increase (depending on how much your pushing it) Hope this helps :)
Use a periodic table, It should help
