If the force on the tympanic membrane (eardrum) increases by about 1.5 N above the force from atmospheric pressure, the membrane can be damaged. When you go scuba diving in the ocean, below what depth could damage to your eardrum start to occur? The eardrum is typically 8.2 mm in diameter.

Table 12.1 Densities of Some Common Substances

*To obtain the densities in grams per cubic centimeter, simply divide by 10³.

Density (kg/m)* Density (kg/m)* Material Material 7.8 x 103 Air (1 atm, 20C) 1.20 Iron, steel 0.81 x 103 8.6 x 103 Brass Ethanol 0.90 x 10 8.9 x 103 Benzene Copper 0.92 x 103 10.5 x 103 Ice Silver 1.00 x 10 11.3 x 10 Water Lead 1.03 10 13.6 x 103 Seawater Mercury 1.06 x 103 19.3 x 103 Blood Gold 1.26 x 103 21.4 x 10 Glycerine Platinum 2 x 103 1010 Concrete White dwarf star Aluminum 2.7 x 103 1018 Neutron star