A stone falls from rest from the top of a cliff.

A second stone is thrown downward from the
same height 3.3 s later with an initial speed of
64.68 m/s. They hit the ground at the same
time.
The acceleration of gravity is 9.8 m/s2 .
How long does it take the first stone to hit
the ground?

To find the time it takes for the first stone to hit the ground, we can utilize the equations of motion. Let's break down the problem step by step:

The first stone is dropped from rest, so its initial velocity (u) is 0.

The equations of motion we'll be using are:
1. v = u + at
2. s = ut + (1/2)at²
3. v² = u² + 2as

Using Equation 1 for the first stone, where v is the final velocity (which is also 0 since it hits the ground), we have:
0 = 0 + (9.8)t

Simplifying, we find:
0 = 9.8t

Since we're looking for the time, t, it must be equal to 0. Therefore, the first stone takes 0 seconds to hit the ground.

Please note that the question assumes negligible air resistance.

11s