physics
posted by margaret .
A stone is thrown straight up from the ground with an initial speed of 30.5 m/s . At the same instant, a stone is dropped from a height of h meters above ground level. The two stones strike the ground simultaneously.Find the height h. gravity is 9.8 m/s2 .
Answer in units of m
The acceleration of

t(up) = (Vf  Vo) / g,
t(up) = (0  30.5) / 9.8 = 3.11m.
t(dn) = t(up) = 3.11s.
T=t(up) + t(dn) = 3.11 + 3.11 = 6.22s =
Time in flight.
The 2 stones were in flight for the same period of time:
T1 = T2 = 6.22s.
h = Vo*t + 4.9t^2,
h = 0 + 4.9*(6.22)^2 = 189.6m. 
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