p 2 * c 2+m 2 * c 4 = m 2 * c 4

p 2 = (m 2-m 2) * c 2 = (m+m) *. M * c 2

is derived from the second formula,

p 2 = (m+m) (m-m) * c 2

, ek = p 2/(m+m)

Extended data:

Momentum.

the momentum of a particle group is the vector sum of the momentum of each particle in the group.

momentum is a conserved quantity, which means that the sum of momentum is constant in a closed system (free from external force or the sum of external force vectors is zero).

the mechanical motion of an object does not occur in isolation, but there is interaction between it and the surrounding objects. This interaction is manifested in the transmission (or transfer) process of mechanical motion between the moving object and the surrounding objects. Momentum is measured from the perspective of mechanical motion transmission, and this transmission is carried out in equal quantities. How much mechanical motion (that is, momentum) is transmitted to object 1 by object 2, object 2 will lose the same amount of momentum, and the result of transmission is both.

from a dynamic point of view, force reflects the speed of momentum transfer.

Reference: Baidu Encyclopedia-Momentum