The flux or power of radiated light is proportional to the electric field squared, ie. f e2 where k' + ik" is if there is absorption of this radiation in a medium, then the wavenumber k complex. show that in this case the time averaged flux is given by f=foe xp (-2° . i where the averaging is done over a time period much longer than the period of the oscillation. what must be the sign of k"? explain in words, and with a drawing, what k" > 0 implies for what happens to the flux of radiation as it propagates through an absorbing medium.

A23 kg log of wood begins from rest, 300 m up a sluice (a water track used to transport logs, think of it as an inclined plane with negligible friction) inclined at 20° to the horizontal. after it reaches the flat waterway at the bottom it collides elastically with a 100 kg block of wood initially at rest near the base of the incline. (a) how long does it take the 23 kg log to travel down the incline? (b) what is the speed of the 23 kg log at the bottom of the incline? (c) what are the velocities of both blocks of wood after the collision? (d) what is the total kinetic energy before the collision? (e) what is the kinetic energy of the 23 kg log after the collision? (f) what is the kinetic energy of the 100 kg block of wood after the collision? (g) what is the total kinetic energy after the collision? (h) compare the total initial and total final kinetic energies. is this consistent with what you would expect for elastic collisions? explain!

Observations show that interstellar clouds can have almost any shape and

What is the kinetic energy of a baseball moving at a speed of 40 m/s if the baseball has mass of 0.15 kg?