The bulk modulus of a substance is the radio of a small decrease in pressure to the result...

The bulk modulus of a substance is the radio of a small decrease in pressure to the resulting fractional increase in volume:

Show that B = (5/3)P, in the free electron gas model, and use your result in Problem 5.16(d) to estimate the bulk modulus of copper. Comment: The observed value is 13.4 × 1010 N/m2, but don't expect perfect agreement — after all, we're neglecting ail electron-nucleus and electron-electron forces! Actually, it is rather surprising that this calculation comes as close as it does.