Question

25. An apple is launched directly upward at 64 feet per second from a platform 80 feet high. The equation for this
apple's height h at time t seconds after launch is h - 16t? + 646 + 80.
a Find the maximum height reached by the apple.
b. How many seconds will it take for the apple to return to the ground.

Answer 1

Answer:

a. 144 ft

b. 5 s

Step-by-step explanation:

h = -16t² + 64t + 80

a. This is a parabola, so the maximum height is at the vertex.

t = -64 / (2 × -16)

t = 2

h = -16(2)² + 64(2) + 80

h = 144

The apple reaches a maximum height of 144 ft.

b. 0 = -16t² + 64t + 80

0 = t² − 4t − 5

0 = (t + 1) (t − 5)

t = -1 or 5

t must be positive, so it takes 5 seconds to reach the ground.