Answer:
The rate of change in distance between the spy and the rocket is 10.8 km/min,
or about 180 m/sec.
Step-by-step explanation:
At "Time=0" the rocket is 6km from the spy.
The rocket travels vertically 8km in about 0.37 minutes, calculated by 8km÷21.6km/min.
At that point, the rocket is 10 km from the spy., calculated by 6²+8²=10²
The difference is 4 kiilometers over 0.37minutes, about 22.2 seconds
Divide Distance by Time to get Rate:
4km/0.37min = 10.8 km/min
That is about 180 meters per second.