Please help with physics/Calculus problems

[hd28cw]

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[dextercioby]

I saw only 4 problems in the document.The third one (with the charged sphere) is trivial.The formula reads (i'm a theorist,so i'll let u put in the numbers)
Q=\frac{\rho}{8}\frac{4\pi}{3}(r_{1}^3 -r_{2}^3) .
Pay attention with the units(centimeters for radius,Coulomb/cubic meter for the volume charge density). I hope u see where that "8" is coming from.If u don't,try to learn basical geometry before any phyiscs.

Daniel.