Question

A pebble falls off a cliff at a height of

Answer 1

Answer:

Step-by-step explanation:

The equation for this free fall problem is

$h(t)=-16t^2+1296$ where h(t) is the height of the pebble from the ground at any time t. If we are looking for the time it takes the pebble to hit the ground, knowing that at ground level the height is 0, we set the quadratic equal to 0 and solve for t:

$-16t^2+1296=0$ and

$-16t^2=-1296$ and

$t^2=81$ so

t = -8, 8

Since time will never be negative,

t = 8 seconds