Final answer:
The rate of change of the distance between the spy and the rocket when the rocket is 8 km in the air is 17.28 km/min.
Step-by-step explanation:
To find the rate of change of the distance between the spy and the rocket, we can use the concept of related rates.
Let's consider the distance between the spy and the rocket at any given time as d, and the height of the rocket at that time as h.
We know that the rocket travels upwards with a velocity of 21.6 km per minute. This means that the rate at which the height of the rocket is changing is 21.6 km/min.
Using the Pythagorean theorem for right triangles, we can relate the distance and height:
d^2 = 6^2 + h^2
Differentiating both sides with respect to time, we get:
2d(dd/dt) = 2h(dh/dt)
Let's substitute the values we know: when the rocket is 8 km in the air, we have d = 6 km and h = 8 km. We also know that dh/dt (rate at which the height is changing) is 21.6 km/min.
Now, we can solve for d(dt/dd) to find the rate of change of the distance:
d(dt/dd) = (2h(dh/dt))/(2d)
Substituting the values, we have: d(dt/dd) = (2 * 8 * 21.6)/(2 * 6) = 17.28 km/min