The conversion of 1 atomic mass unit (amu) to 931.5 MeV/c² is derived from Einstein's equation E=mc², which relates mass and energy. To understand this conversion, one must first know the mass of 1 amu in kilograms. Additionally, converting joules to electron volts (eV) is necessary, as 1 MeV equals 1 million eV. This relationship illustrates how mass can be expressed as energy in the context of particle physics. The explanation clarifies the connection between mass units and energy measurements.