Which concept explains why frequencies of light that fell below the frequency threshold of the metal did not eject electrons? *

Is it possible to use the energy from two atoms colliding to create a clean burning lasting fuel source with a large amount of force? is it also possible to harness that energy from the two atoms colliding to create a clean energy source that will last for years from just two atoms colliding. is there a possibility to control and store that energy for years but slowly let the energy out enough to power cities cheaper and faster.

What are similarities and differences of reflection, refraction, diffraction and absorption?

Which situation will produce the greatest change of momentum