Question

A projectile is thrown upward so that its distance above the ground after t seconds is h = -16t2 + 672t. After how many seconds does it reach its maximum height?
A) 21 s
B) 31.5 s
C) 42 s
D) 10 s

Answer 1

Take the derivative and set it equal to zero! That will give time that the velocity is at zero..Max height is one of the points that velocity is zero.

Answer 2

I would say 21 s

Answer 3

I'm still confused

Answer 4

you have a distance function and the derivative of position is velocity. Therefore to fine the max distance we take the derivative of the function and set it to zero and solve for zero.

Answer 5

Oh I get it, thank you!