# Homework Help: Velocity of Sound, speed of rock and return of sound

1. Feb 3, 2010

### Chrisss

1. The problem statement, all variables and given/known data
Rock is thrown vertically towards a bell 50m away, you hear the bell ring 4.5 seconds later, how fast was the rock travelling, assuming the speed of sound is 330m/s

2. Relevant equations
d=v/t

3. The attempt at a solution
I like to draw my questions out, then fill in the data, so i'll do that first, if you don't wish to see it please scroll down a bit
4.5 seconds for return of sound
<-----------------
--------------------bell
^Starting position 50m
Speed of sound 330m/s
Distance 50m
4.5 seconds for sound to return from throwing it

Now, first I wanted to find how long it would take the sound to get back after it hit the bell so I looked for time
T = D/V

T=50m / 330mps
0.15151515s

I then tried to find the velocity it would take for the rock to reach the bell on it's own,
so I looked for the time again, from which I could distract the time it took for the sound from

V = D/T
V = 50m / 4.5s
V = The rock was going for 11.11111mps IF the sound was instantaneous, I've no idea how to subtract 0.15151515s from 11.11111mps

I don't know if I missed something during instruction, but I've just started physics and this could be stupid, but I've no clue where to go from here.