A 15,800-kg truck is moving at 12.0 m/s when it starts down a 6.00 incline in the Canadian Rockies. At the start of the descent the driver notices that the altitude is 1630 m. When she reaches an altitude of 1440 m, her speed is 29.0 m/s. Find the change in (a) the gravitational potential energy of the system and (b)the trucks kinetic energy. (c)Is the total mechanical energy of the system conserved? Explain.

Chapter 30: Quantum Physics The “ideal” blackbody absorbs all the light that is incident upon it and is an ideal radiator The distribution of energy in blackbody radiation is independent of the material from which the blackbody is constructed — it depends only on the temperature, T Classical predictions were that the intensity increased rapidly with frequency, hence the ultraviolet catastrophe. Planck’s constant is a very tiny number; this means that the quantization of the energy of blackbody radiation is imperceptible in most macroscopic situations A more intense beam of light will contain more photons, but the energy of each photon does not change The photoelectric effect occurs when a beam of light strikes a metal