Aunit of measure for work besides joules

Niobium forms a substitutional solid solution with vanadium. compute the number of niobium atoms per cubic centimeter for a niobium-vanadium alloy that contains 24 wt% nb and 76 wt% v. the densities of pure niobium and vanadium are 8.57 and 6.10 g/cm3, respectively

Let f(x) = x4- 8x2 . find the relativeextrema of this function using the second derivative test.

Aball is thrown horizontally from a cliff at 8m/s .in what direction is the ball moving 2s later?