Weakness in what muscle can lead to chronic back pain?

Heat from earths interior and pressure from overlying rock transform the remains of marine sediments into

How does friction with the atmosphere affect the speed of an artificial satellite

How can a geological time scale best be reconstructed? a) comparing vestigial structures in living species b) comparing homologous structures in living species c) examining homologous structures in fossil remains d) examining the written records of scientists from past cultures