To get you thinking scientifically about what happens when you lean against a wall try the following exercise imagine that you hold an empty pitcher and begin filling with water in what direction will it feel like the pitcher is trying to move as it fills

Aphysical change is one that you can put in and remove like a ham sandwich. the stuff you put in there can be changem its not permanet. a chemical change is on that can't be change thats permanet. like when you make a cake and bake it. you can't get those ingredients back.