In your own words, explain how energy is involved in physical changes and in chemical change

During phase changes, energy changes are usually involved. For example, when solid dry ice vaporizes (physical change), carbon dioxide molecules absorb energy. Meanwhile, when liquid water becomes ice energy is released. Remember that all chemical reactions involve a change in the bonds of the reactants.

0.11 m/s and 0.28 m/s should be correct

no simpler subs form complex ones. synthesise = make