A) for a solar eclipse to occur, the moon must be located between the earth and the sun. however, both the earth’s and the moon’s orbits are not circles but ellipses. the distance between the earth and the moon varies between 357,000 and 407,000 km. the distance between the earth and the sun varies between 147.1 × 106 and 152.1 × 106 km. calculate the range of solid angles under which the moon and the sun can appear, and decide which orbit is more important to make a solar eclipse total or not anywhere on earth. (use these radii: earth: 6371 km; moon: 1737 km; and sun: 696,000 km.)
b) even if the combination of distances should make a solar eclipse total, it is not always total. why could that be?
c) due to tidal friction, the mean earth-moon distance increases by 3.8 cm/year. how many more years will total solar eclipses be possible on earth? (source of numerical values: nasa planetary fact sheets)

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 ..

Nitrogen (n2) undergoes an internally reversible process from 6 bar, 247°c during which pν1.2 = constant. the initial volume is 0.1 m3 and the work for the process is 121.14 kj. assuming ideal gas behavior, and neglecting kinetic and potential energy effects, determine heat transfer, in kj, and the entropy change, in kj/s. show the process on a t-s diagram.

In a hydrogen molecule there are a total of four charges, 2 protons in the two nuclei, and 2 electrons. how many unique charge-pairs are there (without double counting)?