how long does it take for a rock that is falling down from a distance of 200ft high?
what is the formula is used for this problem?
Note that an object falling freely experiences uniformly accelerated motion (UAM).
In this case, we can use the formula,
h = vo * t - (1/2) * g * t^2
where
h = height or distance
vo = initial velocity
t = time
g = acceleration due to gravity = 9.8 m/s^2 = 32.2 ft/s^2
Since the rock came from rest, the initial velocity (vo) is zero. The formula becomes,
h = - (1/2) * g * t^2
Substituting,
200 = -(1/2) * (-32.2) * t^2
200 = 16.1 * t^2
12.422 = t^2
t = 3.52 s
Note that the gravitational constant, 32.2, has a negative sign because it's direction is downward (acceleration in a vector quantity so its direction is important).
Hope this helps~ `u`