AQA A-Level Physics/Mass and energy
E=mc² This is the energy-mass equivalence. From this equation, we know that 1 kg of mass is equal to 2.998*10^8 J. Similarly, when 0.5 kg of matter comes into contact with 0.5 kg of antimatter, they both annihilate each other and their masses add up giving a total of 1 kg of mass thus producing 2.998*10^8 J. However the antimatter and matter do not just disappear into thin air, instead they are broken up to form smaller particles. This equation also tells us that when an object moves faster it has more kinetic energy and thus slightly more mass.