Solving initial velocity for falling object

[heythere1010]

Homework Statement

A stone is dropped from a bridge that is 65 m high. A second stone is thrown downwards 2 seconds later. Both the stones are heard hitting the water at the same time. The speed of sound is a constant 343 m/s. What is the initial velocity of the second stone.

Homework Equations

d=vi*t+1/2at^2

The Attempt at a Solution

65=0+1/2(-9.8)(t)^2

I know t-2 is used for the time of the second stone. I don't know which equations to use to make them equal.

 

[gneill]

Your Relevant equation should suffice.

What value did you get for the time of fall for the first stone? So what must be the time (numeric value) that the second stone has to make the complete journey?

 

[heythere1010]

Your Relevant equation should suffice.

What value did you get for the time of fall for the first stone? So what must be the time (numeric value) that the second stone has to make the complete journey?

5.2. Do I just sub it into the second equation with t-2 and solve for initial velocity?

 

[haruspex]

5.2. Do I just sub it into the second equation with t-2 and solve for initial velocity?

Sure.

 

[heythere1010]

Sure.

So the speed of sound is irrelevant?

 

[haruspex]

So the speed of sound is irrelevant?

The sounds of hitting the water were heard at the same time. Did they hit the water at the same time?