Wind speed is measured using an/a

Need on these last 2 questions on my social studies homework 5 and 6 then i’m done with the homework

Complete the square for 3x2 - 12x = 9.

Ascientist performs an experiment where she measures the mass of a piece of metal, pours acid onto the metal, washes the metal, and then re-measures the mass of the metal. the scientist repeats the experiment several times, each time increasing the amount of acid used. the dependent variable in the experiment is the: initial mass of the metal final mass of the metal amount of acid used washing the metal