U3.L4.HW: Quadratic Functions: Question 20

Question

Answer first. Then explain your answers below.

NASA launches a rocket at t=0 seconds. Its height, in meters above sea-level, as a function of time is given by h(t) = -4.9t² + 115t + 241. 

Assuming that the rocket will splash down into the ocean, at what time does splashdown occur?

The rocket splashes down after __________ seconds.

How high above sea-level does the rocket get at its peak? 

The rocket peaks at _________ meters above sea-level.

Answer 1

-4.9t^2 + 115t +241 = 0

solve for t

t = 115/9.8 + (1/9.8)sqr(115^2 +4(4.9)(241))

at the peak

-9.8t +115 =0

t = 115/9.8 seconds to reach max height

max height

= h(115/9.8)

= -4.9(115/9.8)^2 + (115/9.8)t + 241