Sir william herschel counted the number of stars in different directions, and getting similar numbers in each direction along the disk, concluded the sun was near the center of a disk like collection of stars. herschel came to the wrong conclusion about the sun's location because(a) he was predisposed to believe the sun is the center of the milky way, and ignored the data which disagreed with that conclusion. (b) he did not know that interstellar dust made it hard from him to see a large part of the milky way's disk. (c) he only counted globular cluster, and not regular stars. (d) the sun's position in the milky way at that particular time was very unusual and skewed in his results.

The transfer of heat through the movement of a gas or liquid a. convection b. conduction c. radiation

In a thunderstorm, charge builds up on the water droplets or ice crystals in a cloud. thus, the charge can be considered to be distributed uniformly throughout the cloud. for the purposes of this problem, take the cloud to be a sphere of diameter 1.00 kilometer. the point of this problem is to estimate the maximum amount of charge that this cloud can contain, assuming that the charge builds up until the electric field at the surface of the cloud reaches the value at which the surrounding air breaks down. this breakdown means that the air becomes highly ionized, enabling it to conduct the charge from the cloud to the ground or another nearby cloud. the ionized air will then emit light due to the recombination of the electrons and atoms to form excited molecules that radiate light. in addition, the large current will heat up the air, resulting in its rapid expansion. these two phenomena account for the appearance of lightning and the sound of thunder. take the breakdown electric field of air to be eb=3.00ă—106n/c. part a estimate the total charge q on the cloud when the breakdown of the surrounding air is reached. express your answer numerically, to three significant figures, using ďµ0=8.85ă—10â’12c2/(nâ‹…m2) .

Immediately upon reaching its lowest point, a falling pendulum bob has its greatest amount of energy, which is the initial amount of potential energy. a. heat; less than b. heat; more than c. kinetic; less than d. kinetic; more than