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S(t)=-16t^2+16t+5 Projectile motion problem, help thanks?
find the max altitude and the time it reached in seconds
i put it in vertex form -16(t-1/2)^2+9 V(1/2,9) is the max altitude reached 9ft and the secs F(1/2) = 5 secs?
1 Answer
- 1 decade agoFavorite Answer
I would do it with calculus, derivative is -32t + 16
set it equal to zero 0=-32t+16
so your max occurs at time -16/-32 or 1/2 seconds
plug that mofo in and you get -16(.25)+16(.5)+5
so max height is -4+8+5=9
so you are right about the max height being 9 feet, but the time is .5 seconds
if you dont believe me, plug 9 in for S(t) and you get 9=-16t^2+16t+5
simplify you get t^2+t-(1/4)=0 quadratic says t=1/2
Source(s): my brains
