What is spectroscopy? a)the use of ccds to capture light more ef? ciently than with photographic ? lm b)an analysis of the way in which atoms absorb and emit light c)a study of the geometry of rainbows d)a method to freeze atmospheric turbulence for better resolution e)an observational technique to measure the brightness of light at different color?

Can anybody me with this? ? (picture included.)

Consider a double atwood machine constructed as follows: a mass 4m is suspended from a string that passes over a massless pulley on frictionless bearings. the other end of this string supports a second similar pulley, over which passes a second string supporting a mass of 3m at one end and m at the other. using two suitable generalized coordinates, set up the lagrangian and use the lagrange equations to find the acceleration of the mass 4m when the system is released. explain why the top pulley rotates even though it carries equal weights on each side.

Am i correct on these two physics questions?