A young woman is standing on a bridge overlooking a river. If she drops a rock from the bridge, and it takes 1.2 seconds for it to hit the river, how many meters did the rock fall?

We have the position at any time is given by

P = -9.8t^2 + v_{0}t + h where v_{0} = 0.... and let P = 0 when it hits the water.....so we have

0 =-9.8t^2 + h and at 1.2 sec, we have

9.8(m/s^2)(1.2 s)^2 = h = about 14.1 m

http://www.flashcardmachine.com/module-9an-introductiontothephysicsofmotion.html

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Thanks anon for that flash card site. It looks like it could be really useful for students.

Do you use it yourself or did you just google this question?