The mean mass density of stars in the disk of the galaxy is observed to vary with the height z above the galactic plane as p+(z) = p4,0 e-17\/h* close to the sun, where px is the density of stars in the plane, and hx is a scale height (p+,0 and h+ are constants at the location of the sun). the density of the interstellar gas p, is also found to vary exponentially with height at the sun's location, with pg(z) = 29,0 e 17\/hg, where pg,0 and hg are constants. observations show that h+ = 250 pc, while hg =150 pc and that numerically, p+,0 = 6 p9,0. what is the ratio of the surface density of stars, et, to that of gas, eg, at the sun's distance from the galactic center? (hint: how do you convert from volume density to surface density?

Acommon technique in analysis of scientific data is normalization. the purpose of normalizing data is to eliminate irrelevant constants that can obscure the salient features of the data. the goal of this experiment is to test the hypothesis that the flux of light decreases as the square of the distance from the source. in this case, the absolute value of the voltage measured by the photometer is irrelevant; only the relative value conveys useful information. suppose that in part 2.2.2 of the experiment, students obtain a signal value of 162 mv at a distance of 4 cm and a value of 86 mv at a distance of 5.7 cm. normalize the students' data to the value obtained at 4 cm. (divide the signal value by 162.) then calculate the theoretically expected (normalized) value at 5.7 cm.