Energy density of a vibrating solid (8 points) the density of kinetic energy at a given point in a vibrating solid where m is the mass of a single atom and a is the bond length. the density of potential energy is ()', where is the spring constant of a bond. (a) for some reason, somebody decides to write a wave as u = a sin(kx-wi) instead of in complex exponential form. tell me for which positions/times the potential energy density is larger than the kinetic energy density. it might to remember that the speed of sound is a c/m. (b) now somebody produces a wave of the form u(xt) = a sin kr sinwt. are the kinetic and potential energy always in phase or not? explain.

During physical science, ms. greene challenged her students to produce an energy transformation. james and jill wrapped a 4-inch nail with a coil of fifty turns of wire. they connected one end of the coil to one terminal of a knife switch. they connected the other terminal of the knife switch to the battery. finally, they connected the end of the coil to the other terminal of the battery. james held the tip of a 1-inch nail near the flat end of the 4-inch nail. jill closed the knife switch quickly and then opened it. the 1-inch nail was pulled toward the 4-inch nail. what is the best explanation of why the nail moved? a) electrical energy was converted to mechanical energy in the 1-inch nail. b) the 4-inch nail became an electromagnet and the magnetic force attracted the 1-inch nail. c) the electric current in the 4-inch nail was converted to mechanical energy in the 1-inch nail. d) the 4-inch nail had a positive charge and the 1-inch nail had a negative charge. opposites attracted.

The x-coordinate of a particle in curvilinear motion is given by x = 3.1t3 - 4.9t where x is in feet and t is in seconds. the y-component of acceleration in feet per second squared is given by ay = 2.3t. if the particle has y-components y = 0 and vy = 5.0 ft/sec when t = 0, find the magnitudes of the velocity v and acceleration a when t = 1.8 sec. sketch the path for the first 1.8 seconds of motion, and show the velocity and acceleration vectors for t = 1.8 sec. answers: v = ft/sec a = ft/sec2

Which lists the pairs of plates in order from least to greatest in terms of the work done to move the electron?