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Claymore
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Homework Statement
A soccer player kicks a rock horizontally off a 40.0-m-high cliff into a pool of water. If the player hears the sound of the splash 3.00s later, what was the initial speed given to the rock? Assume the speed of sound in air to be 343 m/s.
Homework Equations
Well to start off I have a graph which I don't know how to put it in here. To get things started I am currently taking General Physics and it seems a bit confusing than I thought.
Teacher gave us this:
r= x= ro + Vox t
y= Yo + Voy t + (gt^2)/2
v= Vfx= Vox
Vfy= Voy + gt
Im not sure if there's more to this ^
To my understanding where r= displacement if I am correct, and v is velocity(speed)
it seems that i plug in numbers and calculate them but I am having problem understanding the letters what they represent so i can't get to my solution or explain that, that's my solution. It may sound confusing
The Attempt at a Solution
Height= 40m
a=g=9.8 m/s^2
speed of sound= 342m/s
Time=3s
r = r0 + Vot + (gt^2)/2
= 0 + 342 m/s *3.0s -4.9m/s^2 * 3.0s^2
= 984.9 m
so then I used:
x = x0 Voxt
984.9m = 0 + Vox * 3s
Vox= 328.3 m/s
and:
y= y0 + Voyt + (gt^2)/2
40m= 0 + Voy*3 + -4.9m/s^2 * 3.0s^2
Voy= -28m/s
and I am stuck :( any help on what/how to get intial Velocity. Thanks in advance
Im new to forums as well :P