why do prescribed drugs need to be prescribed by doctors what can happen if you abuse these drugs without a pressure?

Aray of light traveling parallel to the principal axis of a concave mirror will be reflected through the mirror's

Within a pendulum, as potential energy decreases, energy increases. a. heat b. kinetic c. frictional d. gravitational

Consider an insulating crystal, made up of layers of atoms. what form would you expect the temperature dependence of the phonon heat capacity to approach at extremely low temperatures if the interlayer coupling is i)very strong (rigid coupling), and ii) very weak. explain.