planeparatm consider an isothermal atmosphere on the surface of a star, which has a very small height and is in hydrostatic equilibrium. this means that the atmosphere can be treated as plane parallel: in the equation of hydrostatic equilibrium, dp/dr can be replaced by dp/dz, where z is the height above the surface of the star. moreover, the surface gravity, g, is constant over the height of the atmosphere (a) under these assumptions, start with the equation of hydrostatic equilibrium and derive a differential equation for the density of this atmosphere (b) solve this equation to obtain the density as a function of height above the surface of the star (c) in your solution, identify the "scale height," i. e. a quantity with dimensions of length, which represents the height over which the density of the atmosphere changes appre- ciably. (d) calculate the pressure at the base of the atmosphere. (e) using the ideal gas equation of state and your solution for the density structure of the atmosphere from part (b), compute the pressure at the surface of the star. compare your answer to what you found in part (d). what do you conclude from this exercise?

Ais not a compound machine. a. bolt b. shovel c. handcart (dolly) d. see-saw (teeter totter)

Dinate system, and a charge q = - 2.00 nc is placed s2 10 n> c. (a) what is the change in electric potential energy when the dipole moment of a molecule changes its orientation with respect to es from parallel to perpendicular? (b) at what absolute temperature t is the average translational kinetic energy 32 kt of a molecule equal to the change in potential energy calculated in part(: abovethistemperature,thermalagitationprevents the dipoles from aligning with the electric field.) placed in a uniform electric field e with magnitude 1.6 * 6 on the positive x-axis at x = 4.00 cm. (a) if a third charge q3 = +6.00 nc is now placed at the point x = 4.00 cm, y = 3.00 cm, find the x- and y-components of the total force exerted on this charge by the other two. (b) find the magnitude and direction of figure p21.62 ll uu 21.55 . torque on a dipole. an electric dipole with dipole moment ps is in a uniform external electric field es. (a) find the orientations of the dipole for which the torque on the dipole is zero. (b) which of the orientations in part (a) is stable, and which is unstable? (hint: consider a small rotation away from the equi- librium position and see what happens.) (c) show that for the stable orientation in part (b), the dipole’s own electric field tends to oppose the external field. 21.62 ..

Write a hypothesis about the effect of increasing resistance on the current in the circuit. use theformat and be sure to answer the lesson question. “how do changes in voltage or resistance affect current in an electric circuit? ”