Answer:
Rocket will go to a height of 8.678 m
Step-by-step explanation:
Mass of the rocket m = 50 gram = 0.05 kg
Spring constant k = 1050 N /m
Spring is stretched to 9 cm
So x = 0.09 m
Work done in stretching the spring

From energy conservation this energy will convert into potential energy
Potential energy is equal to
, here m is mass, g is acceleration due to gravity and h is height
So


So rocket will go to a height of 8.678 m