The equation of motion
s= ut + 1/2 at^2
can be used to solve this question. In this equation, s is the distance traveled, u is the initial velocity, t is the time taken and a is the acceleration.
Since, the rock is dropped, the initial velocity of the rock is 0 m/s. That is,
u = 0 m/s
The acceleration of the rock would be equal to the acceleration due to gravity, g. The value of g (approximately) 9.81 m/s^2 or 32.2 ft/s^2.
And, time taken for the rock to hit the ground, t = 3 s.
Substituting the values of u, t and a in the equation, we get:
s = 0 x 3 + 1/2 x 32.2 x 3^2 = 144.9 ft.
Thus, the rock dropped from the window will travel a distance of about 144.9 ft before hitting the ground.
Hope this helps.