Posted by **Hannah** on Monday, September 13, 2010 at 11:33pm.

At t = 0, a stone is dropped from a cliff above a lake; 2.0 seconds later another stone is thrown downward from the same point with an initial speed of 33 m/s. Both stones hit the water at the same instant. Find the height of the cliff.

- Physics -
**Alura**, Monday, September 13, 2010 at 11:43pm
I have just recently had to answer a very similar question. My prof. has given me the two general eqns to use:

Y(final)=Y(initial)+V(initial)((T(final)-T(initial))+1/2a(T(final)-T(initial))^2

and

V(final)=V(initial)+a(T(final)-T(initial))

From there, write down your knowns and derive more specific eqns from the general ones... Very vague i know...good luck

- Physics -
**drwls**, Monday, September 13, 2010 at 11:44pm
Y1 = -(g/2) t^2

Y2 = -33(t-2) -(g/2)((t-2)^2

Set Y1 - Y2 and solve for t.

Use that t to compute Y at that time.

- Physics -
**Hannah**, Tuesday, September 14, 2010 at 3:28pm
when i solve for t I get an extremely small number like .1998. I don't think I am setting up the problem right or something.

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