(adsbygoogle = window.adsbygoogle || []).push({}); TWO questions!! Distance to exp. 120dB AND Depth of Well

I've got two questions here. I've worked on both of them, and now I'm stuck...

1)A stone is dropped from rest into a well. The sound of the splash is heard exactly 1.60 s later. Find the depth of the well if the air temperature is 10.0°C.

So, Vnot=0 m/s, delT=1.6s, a=9.8 m/s, temp=10C, and I figured out the speed of sound in 10C to be 337 m/s, but where do I go from here?

-----------------------------------------------------------------------

2) An outside loudspeaker (considered a small source) emits sound waves with a power output of 100 W.

I've already found the intensity at 12.5m to be .0509W/m^2, and the intensity level in dB at that distance to be 107.1 dB.

The question now asks: At what distance would you exp. the sound at the threshold of pain, 120dB

Work - which i'm not sure is correct -

B=10 log (I/Iref) Iref = 1.0 x 10^-12

so... 120dB = 10 log (I/Iref)

12=log (I/Iref)

10^12=(I/1.0x10^-12)

10^12/1.0x10^-12= I = 1 m

I don't think thats right... Did I use the correct forumla

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: TWO questions Distance to exp. 120dB AND Depth of Well

**Physics Forums | Science Articles, Homework Help, Discussion**