Question

Jack drops a stone from rest off of the top of a bridge that is 23.4 m above the ground. After the stone falls 7.2 m, Jill throws a second stone straight down. Both rocks hit the water at the exact same time. What was the initial velocity of Jill's rock

Answer 1

Explanation:dropped stone hits water:

24.4-4.9t^2=0

t=2.23

stone has fallen 6.6m:

4.9t^2 = 6.6

t = 1.16

So, Jill's thrown stone only has 2.23-1.16=1.07 seconds to hit the water:

24+1.07v-4.9*1.07^2 = 0

v = -17.19 m/s