Question

The height (in feet) of a rocket from ground level is given by the function f(t) = -16t2 + 220t. What is the instantaneous velocity of the rocket 12 seconds after its launch?

Answer 1

-164 ft/second.

Explanation:

The instantaneous velocity is given by the derivative;

f(t) = -16t^2 + 220t

V = f'(t) = -32t + 220

So at 12 seconds:

V = -32*12 + 220

= -164 ft/second ( It is negative because it is descending).