Amplitude and Pressure Wave: Pa Homework

[bnwchbammer]

Webassign night again!

Homework Statement

During normal conversation, the amplitude of a pressure wave is 0.023 Pa.
(a) If the area of the eardrum is 0.56 cm2, what is the force on the eardrum?
N

(b) The mechanical advantage of the three bones in the middle ear is 1.5. If the force in part a is transmitted undiminished to the bones, what force do the bones exert on the oval window, the membrane to which the third bone is attached?
N

(c) The area of the oval window is 0.026 cm2. What is the pressure increase transmitted to the liquid in the cochlea?
Pa

Homework Equations

I'd assume I'd be using dB=20log(P/P) But I'm not sure how to apply that to any of these equations.

The Attempt at a Solution

Can't even figure out where to start. I'm sure with some starting advice, or at least how to solve the first part I could figure it out.

 

[Dr.D]

Maybe you could start with F = pressure * area

 

[bnwchbammer]

well, to convert cm^2 to m^2 do I have to do anything special besides just dividing by 100?

 

[NBAJam100]

well, to convert cm^2 to m^2 do I have to do anything special besides just dividing by 100?

You have to do more than divide by 100. If it was converting cm --> m dividing by 100 would be ok.

Think of it this way in terms of multiplication- You want to cancel the units until you have m^2.

So-

1cm^2 *(1m^2)/(100^2 cm^2) = .0001 m^2.

So you know there are 100 cm in a meter. So if everything is squared, that must mean that there are 100^2 cm^2 in a m^2. So as you see above, when looking at the units, the cm^2's cancel out and you are left with m^2.

 

[bnwchbammer]

Should'a been able to figure that out, but got it now. 100% on webassign, all right. Thanks for helpin me out guys.