A rocket of mass 500 kg ejects gas at a rate of 10 kg/s with an exhaust velocity of 800 m/s relative to the rocket. What is the thrust force produced by the rocket engine?

Thrust force is given by F = v × (dm/dt), where v is the exhaust velocity and dm/dt is the rate of mass ejection. F = 800 × 10 = 8000 N. Option B incorrectly uses only the exhaust velocity, while option D results from multiplying by the total mass of the rocket.