Question #cd938
1 Answer
Explanation:
We're (essentially) asked to find the time when the rock hits the ground, given it fell from a height of
This rock is undergoing free-fall; i.e. it is under the sole influence of Earth's gravitational force, and falling toward Earth's surface with an acceleration of
To find the time
where
-
yy is the position at timett (-11.5−11.5 "m"m ), -
y_0y0 is the initial position (00 "m"m ), -
v_(0y)v0y is the initialyy -velocity, which is00 since the rock was merely dropped, -
tt is the time, in"s"s (what we must find), and -
gg is9.89.8 "m/s"^2m/s2 (the minus sign in front of the1/212 indicates that this acceleration is downward)
Plugging in known values, we have
When dropped from a well with a depth of