Power is defined in a mathematical expression as P = F x v where F is in N and v is in m/s. From the given equation, the v = d/t which is v = 10/ 6, then substituting the answer to the power formula W = 54 N (10/6 m/s) = 90 Watts.
You can't usually just use a single spectrum line to confirm the identity of an element because there are cases that the emission line id not clearly defined. When the emission line is very weak compared to surrounding noise, in which case the more datapoints you have to build up confidence for the existence of a particular emission spectra, the better.
Mass=volume x density
if we have mass and density we can calculate volume using the formula: volume=mass/density
volume of the displaced water = 600g/19.3g/cm3
volume = 31.09cm3
He was not all the way up the ladder he was only on the first couple steps