Question

A flare is fired from 4 feet above the ground at a speed of 64 feet per second. The flare will fall to the ground after it burns out.

Answer 1

68 feet.

Explanation:

At maximum height, the velocity of the flare will be zero.

If the flare height above the ground is modeled by the equation

h = -16t²+64t+4

Velocity = dh/dt = 0

-32t + 64 = 0

-32t = -64

t = -64/-32

t = 2secs

This shows that the flare reaches its maximum height after 2secs.

To get the maximum height of the flare, we will substitute t = 2s into the equation h = -16t²+64t+4

h = -16(2)² + 64(2)+4

h = -64+128+4

h = 64+4

h = 68 feet

The maximum height of the flare is 64 feet.