TASK DEFINITION: In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.
PROBLEM: The Stratton-Chu model of this phenomenon attempts to improve on earlier scalar models such as the Rayleigh-Sommerfeld theory. The equivalence of complementary arrangements in producing this phenomenon is described by Babinets principle. A simple scalar theory of this phenomenon makes use of an integral named for Kirchhoff and Fresnel, and a simple pictorial model of this phenomenon is given by Huygens principle of wave propagation. FTP name this behavior observed in electrons by Davisson and Germer, the bending of waves as they pass obstacles.

SOLUTION: Science

PROBLEM: This force is represented by a first derivative with respect to position in the harmonic oscillator equation. In one model, this force stems from tiny electrostatic repulsions. It can be understood as the parallel shear component of the contact force, whose other component is typically calculated as mg cosine theta. It is calculated from a coefficient, symbolized mu, multiplied by the normal force. Rolling motion is affected by the "kinetic" type of this force, which is known as "drag" in fluids. For 10 points, name this force that resists the motion of objects against one another.

SOLUTION: Science

PROBLEM: Pneuman and Kopp provided the first ab initio model of this phenomenon by integrating the MHD equation for a dipole source; their model closely matched Parkers 1956 model. Evidence for this object was provided by Biermanns observations of comets, though it was not observed until Luna 1. Its interaction with the terrestrial magnetic field results in the bow shock. It ceases being supersonic at the termination shock and its velocity falls to zero at the heliopause, where it merges with the interstellar medium. Radiation pressure and pressure from this plasma flow cause comet tails to always face away from the center of the solar system. For 10 points, name this stream of particles constantly emanating from the sun.

SOLUTION:
Science