Question

The height (in feet) of a rocket from ground level is given by the function f(t) = -16t2 + 160t. What is the instantaneous velocity of the rocket 3 seconds after it is launched?

Answer 1

32 feet/second
64 feet/second
12 feet/second
10 feet/second
8 feet/second

Answer 2

Is it 64 feet /second

Answer 3

@Abhisar

Answer 4

@Michele_Laino

Answer 5

we have to compute the first drivative of f(t), what do you get?

Answer 6

f'(t) = -32t + 160

Answer 7

ok!
Now the requested velocity is given by the subsequent quantity:
\[v = f'\left( 3 \right) - 32 \times 3 + 160 = ...?\]

Answer 8

oops..
\[v = f'\left( 3 \right) = - 32 \times 3 + 160 = ...?\]

Answer 9

64

Answer 10

that's right!