posted by Emily .
A high diver of mass 65.0 kg steps off a board 10.0 m above the water and falls vertical to the water, starting from rest. If her downward motion is stopped 2.30 s after her feet first touch the water, what average upward force did the water exert on her?
I'm not sure how to go about solving this. I've tried a few different ways but none of them yielded the right answer. Please help.