Transcript: The universe is full of things that are held together by forces: atoms, molecules, solar systems, stars, and galaxies. The binding energy of a system is the energy required to take it apart. For example, a speed of eleven kilometers per second corresponds to the kinetic energy needed to liberate anything from the gravitational binding energy of the Earth, or consider an atom. The binding energy of a hydrogen atom is a tiny quantity, 2.2 x 10-16 Joules. This means that any incoming photon with a frequency greater than 3.3 x 1015 Hertz or a wavelength less than a hundred nanometers gives sufficient energy to the system to liberate an electron.