Special Relativity - Rest Mass

A particle leaving a cyclotron has a total relativistic energy of 10 GeV and a relativistic momentum of 8 GeV/c. What is the rest mass of this particle? 

A. 0.25 GeV/c²
B. 1.20 GeV/c²
C. 2.00 GeV/c²
D. 6.00 GeV/c²
E. 16.0 GeV/c²

(GR0177 #79)

Solution:

E² = p²c² + m₀²c⁴

Given: E = 10 GeV and p = 8 GeV/c

100 = (64/c²)c² + m₀²c⁴
m₀²c⁴ = 100 − 64 = 36
m₀ = 6 GeV/c²

Answer: D