Question

A toy missile is shot into the air. its height h in meters after t seconds can be modeled by the function h(t) = -4.9t^2+15t+0.4
d) when does the toy missile reach its max. height?
e) what is the max. height of the toy?
please help

Answer 1

very rough drawing of the projectile's motion



the max height is when the toy missile starts falling back down.
this is instant point where slope of the parabola is zero (between when it turns from positive to negative, i.e. flying up to flying down)

so you'll want h'(t) = -9.8t + 15. remember that h'(t) represents the slope of the function.

we want the point when the slope = 0.

t = 15/9.8

to find the corresponding height, you plug it back in h(t).

don't hesitate to ask questions :)

Answer 2

oh i understand it now...thank youu!

Answer 3

glad i could help :)