A ball is thrown vertically upward with an initial speed of 80 f/s. Its height after t seconds is given by h=80t−16t^2 a)how high does the ball go and when does the ball hit the ground?

Question

A ball is thrown vertically upward with an initial speed of 80 f/s. Its height after t seconds is given by h=80t−16t^2    a)how high does the ball go and when does the ball hit the ground?

anonymous · Answer

max height of the ball is the second coordinate of the vertex of the parabola. the first coordinate is $-\frac{b}{2a}$ in your case it is $-\frac{80}{2\times -16}=\frac{5}{2}$
to find the actual height, replace $t$ by $\frac{5}{2}$ and see what you get