How Much Energy is Converted from Mass to Kinetic Energy in Uranium Fission?

[musicmar]

Homework Statement

In a fission process, a slow neutron causes a uranium nucleus (m=218943.42 MeV/c^2) to split into a barium nucleus (m=131261.73) and a krypton nucleus (m=85619.32), plus two excess neutrons (actually 3 including the original neutron, but that is present before the process as well), each of mass 939.57. Calculate the energy converted from mass to kinetic energy in this process.

Homework Equations

K= E-mc^2
E^2=p^2c^2+m^2c^4

The Attempt at a Solution

K = E - mc^2
E_bef=E_aft

Not given any velocities, the other formulas I have for energy and momentum are not really helpful. But I know that I will have to find the total energy before and after somehow.

 

[malawi_glenn]

You do not need those equations, you only need to figure out how much rest mass the system has before, and after the process. The difference between those will give you the released kinetic energy. The reason why you can do that here is because the neutron is "slow", its kinetic energy (around and less ~1eV) is much less than its "mass-energy" (939.57 MeV)

I'll give you a hint: the rest mass of the system before the process is
(218943.42 + 939.57) MeV / c²