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Qnslaught
Nov15-09, 11:02 PM
1. The problem statement, all variables and given/known data

An atomic nucleus is in an excited state. It decays to its ground state with the emission of a gamma ray having energy, Egamma = 24.0 keV. The nucleus has a mass of 9.53e-26 kg. What is the recoil speed of the nucleus? (Note: This may be an inelastic collision)


2. Relevant equations
1 eV = 1.6e-19 J



3. The attempt at a solution
I tried setting the final kinetic equal to the rest energy, and I tried setting it equal to the energy of the gamma ray, and I can't get the answer. The answer key lists the correct answer as 134 m/s, and I have no idea how to get to that.

Delphi51
Nov15-09, 11:46 PM
Why not use conservation of momentum?
Use the special formula for the momentum of a photon, using its energy to calculate its momentum.

Qnslaught
Nov16-09, 12:26 AM
Thank you, I got it now :)