Answer
0.32 N.
Work Step by Step
Use equation 10–3b to calculate the change in pressure. Multiply by the eardrum’s area to find the force on the eardrum.
$$\Delta P = \rho g \Delta h$$
$$F = A \rho g \Delta h=(0.20\times10^{-4}\;m^2) (1.29\;kg/m^3) (9.80\;m/s^2) (1250\;m) =0.32\;N$$