Energy and Change
... Some examples of physical change include tearing a piece of paper, bendind a nail,or spinning a wool into yarn. A physical change alters the form of a substance, but does not change it to another substance. Mattercan also change by means of chemical change. ... Whena substance undergoes a chemical change,it is changed into a different substance with different oppertunities. ... To explain changes in matter, scientists talk about the effect of energy.