A train moves east at 15m/s relative to the ground. From inside the train, a passenger throws two identical balls: ball P is thrown east at 10m/s relative to the train, and ball Q is thrown west at 10m/s relative to the train. Ignoring air resistance, what is the ratio KP/KQ of their translational kinetic energies as measured by a stationary observer on the ground?
a) 6.25
b) 1
c) 25
d) 5