I am stumped by the following problem, I can't quite figure out what to do with the information about the speed of sound:(adsbygoogle = window.adsbygoogle || []).push({});

A soccer player kicks a rock horizontally off a 31.0 m high cliff into a pool of water. If the player hears the sound of the splash 3.1 s later, what was the initial speed given to the rock? Assume the speed of sound in air to be 343 m/s.

I don't think it is implying that the object was traveling at the speed of sound, so I'm not really sure how it figures into the problem, since it does not give a delta X value.

The known quantities are delta Y = -31 m and t= 3.1, so using

delta Y= Voyt + (1/2)gt^2 and substituting zero for Voy, I solved for t and got 2.525 seconds.

Using Vy=Voy + at, I got that Vy = 24.647 m/s.

That is where I'm stuck, any advice on where to proceed from here?

Thank you for your time!

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# Homework Help: Two dimensional motion problem: speed of sound as a factor?

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