Question 1123163
A rock is thrown upward with a velocity of 18 meters per second from the top of a 36 meter high cliff, and it misses the cliff on the way back down.  When will the rock be 4 meters from the water, below?  Round your answer to two decimal places.
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You didn't supply the equation for the trajectory.
Another tutor used -9.8t^2 as the squared term, but it's -4.9t^2 (on Earth).