This may seem like a strange question but the answer is at the heart of the relationship between different types of energy. What is the answer?

Your question isn't strange at all. In fact it's a

*very* good question. Since the proper mass of a photon is zero, i.e. m

_{0}, the proper energy E

_{0} = m

_{0}c

^{2} is also zero, i.e. E

_{0} = 0. Since energy is the sum of kinetic energy plus proper energy, i.e.

E = K + E

_{0}It follows that since E

_{0} = 0 that

E = K + E

_{0} = K

i.e.

E = K

Therefore the energy of a photon is 100% kinetic energy.