What would happen if the kinetic energy of the reactants was not enough to provide the needed activation energy

The products would not be formed or the reaction could not be carried out.

Explanation:

Sometimes in these situations it is chosen to place a chemical compound that accelerates the reaction and increases the kinetic energy of the reactants, without altering their chemical composition, and this is called a catalyst, which can be anything from a protein to a macromolecule.

b i think it’s a water wheel turning in a stream