Solving initial velocity for falling object

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Homework Help Overview

The problem involves two stones: one dropped from a height of 65 m and another thrown downwards 2 seconds later. Both stones are heard hitting the water simultaneously, and the speed of sound is given as 343 m/s. The objective is to find the initial velocity of the second stone.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the time of fall for the first stone and how it relates to the second stone's journey. There are inquiries about the relevance of the speed of sound and whether the stones hit the water simultaneously.

Discussion Status

Some participants have provided guidance on using the relevant equations and have prompted questions about the time values needed for both stones. There is an ongoing exploration of the relationship between the two stones' timings and the implications of the speed of sound.

Contextual Notes

Participants are navigating the constraints of the problem, including the timing of the second stone's throw and the assumption that both stones are heard hitting the water at the same time.

heythere1010
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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.
 
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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?
 
gneill said:
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?
 
heythere1010 said:
5.2. Do I just sub it into the second equation with t-2 and solve for initial velocity?
Sure.
 
haruspex said:
Sure.
So the speed of sound is irrelevant?
 
heythere1010 said:
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?
 
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