N the Bohr model of the hydrogen atom, an electron in the lowest energy state moves around the nucleus at a speed of 2.19 × 10 6 m/s at a distance of 0.529 × 10 − 10 m from the nucleus. (a) What is the electric potential due to the hydrogen nucleus at this distance? (b) How much energy is required to ionize a hydrogen atom, whose electron is in this lowest energy state? Assume the electric potential goes to zero as r → [infinity] .

John throws .4 kg ball with velocity of 18 m/s. hits .2 kg bottle and bottle flies 25 m/s. how fast is ball traveling after hitting the bottle?

Suppose water is leaking from a tank through a circular hole of area ah at its bottom. when water leaks through a hole, friction and contraction of the stream near the hole reduce the volume of water leaving the tank per second to cah 2gh , where c (0 < c < 1) is an empirical constant. a tank in the form of a right-circular cone standing on end, vertex down, is leaking water through a circular hole in its bottom. (assume the removed apex of the cone is of negligible height and volume.) (a) suppose the tank is 20 feet high and has radius 8 feet and the circular hole has radius 2 inches. the differential equation governing the height h in feet of water leaking from a tank after t seconds is dh dt = − 5 6h3/2 . if the height of the water is initially 8 feet, how long will it take the tank to empty? (round your answer to two decimal places.)

In the first law of thermodynamics, triangle e=q-w, what does q stand for