Assume the area of an eardrum is about 4.9 x 10^-5 m^2. Find the sound power (energy per second) incident on an eardrum at the threshold of hearing (Io = 1 x 10^-12 W/m^2) in units of W.
Also, find the sound power incident on the eardrum at the threshold of pain (I1 = 1 W/m^2) in units of W.
2006-12-06 11:55:54 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Physics
Looks like a pretty basic set of ratios:
First:
Io=Power/Area.
1e-12W/m^2=Power/4.9e-5m^2
Just solve for Power
Second one's the same with different numbers.
2006-12-06 12:03:24 · answer #1 · answered by joker 2 · 0⤊ 0⤋
For the first part you are given area of eardrum and intensity needed to reach threshold. Intensity is defined as energy per area. Here's what you do: (m^2)*(W/m^2)=W or 4.9 x 10^-5 x 1 x 10^-12.
The second part is similar to the first part. Instead you get intensity for threshold of pain. You should be able to do this by yourself after looking at the first part.
2006-12-06 12:09:14 · answer #2 · answered by Ed Y 2 · 0⤊ 0⤋
Multiply the threshold level by the area of the eardrum to get the power level (in watts) and remember that a watt is one joule/second.
Doug
2006-12-06 12:01:25 · answer #3 · answered by doug_donaghue 7 · 0⤊ 0⤋
a) 1 x 10^-12 W/m^2 * 4.9 x 10^-5 m^2 = 4.9 x 10^-17
b) 1 W/m^2 * 4.9 x 10^-5 m^2 = 4.9 x 10^-5
2006-12-07 20:50:33 · answer #4 · answered by pink_petal 2 · 0⤊ 0⤋