Asodium atom will absorb light with a wavelength near 589 nm if the light is within 10 mhz of the resonant frequency. the atomic mass of sodium is 23. (i) calculate the number of "yellow" photons of wavelength 2 = 589 nm that must be absorbed to stop a sodium atom initially at room temperature (v-600 m/s). [7 marks] (ii) what is the minimum time needed to cool a sodium atom?

Athin plate moves between two parallel, horizontal, stationary flat surfaces at a constant velocity of v = 7.5 m/s. the two stationary surfaces are spaced 4 cm apart, and the medium between them is filled with oil whose viscosity is 0.9 n·s/m2. the part of the plate immersed in oil at any given time is 2 m long and 0.5 m wide. if the plate moves through the mid-plane between the surfaces, determine the force required to maintain this motion. what would your response be if the plate was 1 cm from the bottom surface (h2) and 3 cm from the top surface (h1)? if the plate moves through the mid-plane between the surfaces, the force required to maintain the motion will be n. if the plate was 1 cm from the bottom surface (h2) and 3 cm from the top (h1) surface, the force required to maintain the motion would be n.

Suppose a comet has an orbital period of 309.1 years around the sun. what is it’s average distance from the sun?

Convection currents are caused by differences in what two things?