Question

7. An airplane has a gun that fires bullets straight ahead at the speed of 600 miles per hour when tested on the ground while the plane is stationary. The plane takes off and flies east at 600 miles per hour. Explain whether each of the following is possible for the pilot to measure:
a. When fired directly ahead the bullets move eastward at a speed of 1200 miles per hour
b. When fired in the opposite direction (by turning the gun westward, but not the plane), the bullets drop vertically downward
c. If fired vertically downward (by turning the gun downward, but not the plane), the bullets move eastward at 600 miles per hour while they fall.

Answer 1

Unless the pilot can track a speeding bullet, I don't see how he can take any of those measurements.

I guess he could turn the gun backwards and fire it when passing over an observer. If the observer sees the bullets come straight down, the speeds are ok.