Question

If a ball is thrown directly upward with a velocity of 14 m/s, its height (in meters) after t seconds is given by y = 14t − 4.9t2. What is the maximum height attained by the ball? (Round to two decimal places.)

______ m

After how many seconds is that height attained? (Round to three decimal places.)

______ s

Answer 1

y = 14 t - 4.9 t^2
if you do not know physics or calculus you must complete the square to find the vertex of the parabola.

4.9 t^2 - 14 t = -y

t^2 - 2.857 t = -(1/4.9) y

t^2 - 2.857 t + 1.429^2 = -(1/4.9)y+2.04

(t-1.429)^2 = -(1/4.9)[ y - 10 ]

vertex at height 10 meters and time 1.43 seconds