A model rocket is fired vertically from rest. It has a constant acceleration of 16.4 m/s2 for the first 1.50 s. Then its fuel is exhausted, and it is in free fall. The rocket has a mass of 78.2 g; the mass of the fuel is much less than 78.2 g. Ignore air resistance. What was the downward net force on the rocket after its fuel was spent?