Question

Justin and Elena each launched a toy rocket into the air. The height of Justin’s rocket is modeled by the equation h = –16t2 + 60t + 2. Elena launched his rocket from the same position, but with an initial velocity double that of Justin’s. Which equation best models the height of Elena’s rocket?

h(t) = at2 + vt + h0
h = –16t2 + 60t + 4
h = –32t2 + 120t + 4
h = –32t2 + 60t + 2
h = –16t2 + 120t + 2

Answer 1

Justin's initial velocity is 60 (the coefficient of t). Doubling it gives 120. The acceleration term (−16) and initial height (2) stay the same.

So Elena's equation is h = −16t^2 + 120t + 2.