What is the exhaust velocity of an ideal ramjet flying at 10

What is the exhaust velocity of an ideal ramjet flying at 1000 m/s, assuming the peak combustor stagnation temperature is 4 times higher the freestream stagnation temperature

Solution

4* (1/2)*v1^2 / g = (1/2)*v^2 / g

where

g=9.81 m/s^2

v1=1000 m/s

so we have

4*1000^2=v^2

v=2000 m/s