the rock will be at 11 meters from the ground level after 5.92 seconds
Step-by-step explanation:
The motion of the rock is a free-fall motion, since the rock is acted upon the force of gravity only. Therefore, it is a uniformly accelerated motion, so its position at time t is given by the equation:
where
h = 23 m is the initial height
u = 27 m/s is the initial velocity, upward
is the acceleration of gravity, downward
t is the time
We want to find the time t at which the position of the rock is
y = 11 m
Substituting and re-arranging the equation, we find
This is a second-order equation, which has solutions:
So
The first solution is negative so we neglect it: therefore, the rock will be at 11 meters from the ground level after 5.92 seconds.
Learn more about free fall:
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