Answer:
17.5 m/s²
1.90476 seconds
Step-by-step explanation:
t = Time taken
u = Initial velocity
v = Final velocity
s = Displacement
a = Acceleration
Force

Initial acceleration of the rocket is 17.5 m/s²

Time taken by the rocket to reach 120 km/h is 1.90476 seconds
Change in the velocity of a rocket is given by the Tsiolkovsky rocket equation

where,
= Initial mass of rocket with fuel
= Final mass of rocket without fuel
= Exhaust gas velocity
Hence, the change in velocity increases as the mass decreases which changes the acceleration