Different energy formulas

[Nataly Antonova 1B]

I have found myself confused between equations and

Could someone explain how those are different and when I should use one or another? Thank you lots!

[Devyn Chun 3I]

I think the E = pc equation refers to the energy of a photon in relation to momentum and the speed of light. The other equation relates to the total kinetic energy of an object in relation to its mass and velocity. For the purposes of our class, it refers to the kinetic energy of an electron.

[Sanjana Narayanan 2J]

I believe that the formula EK = 1/2mv^2 refers to the kinetic energy of a particle. This equation also works for larger objects.

[HaleyC 2F]

E=pc is the energy of the photon equation and the Ke=1/2mv^2 is for finding the kinetic energy.