It is found experimentally that the electric field in a certain region of Earth's atmosphere is directed vertically down. At an altitude of 390 m the field has magnitude 60.0 N/C. At an altitude of 240 m, the magnitude is 100 N/C. Find the net amount of charge contained in a cube 150 m on edge, with horizontal faces at altitudes of 240 and 390 m. Neglect the curvature of Earth.

Which property is expressed in distance units? o a. period o b. wavelength o c. speed o d. frequency

The molecular mass of a gas is (select all that apply) a. independent of the type of gas b. the same number as the atomic (or molecular) mass, but measured in grams c. dependent on the temperature d. the mass of a mole of the gas

The center of a long frictionless rod is pivoted at the origin, and the rod is forced to rotate in a vertical plane with constant angular velocity \omega. write down the lagrangian for a bead of mass m threaded on the rod, using r as your generalized coordinate, where r, \phi are the polar coordinates of the bead. (notice that \phi is not an independent variable since it is fixed by the rotation of the rod tobe \phi = \omega * t) solve lagrange's equation for r(t). what happens if the bead is initially at rest at the origin? if it is released from any point ro > 0, show that r(t) eventually grows exponentially. explain your results in terms of the centrifugal force m* \omega ^2 *r.