DIMENSIONAL ANALYSIS PROBLEM:
Joe employs Will to place a solid cylinder of red phosphorus that sits on a weight-sensitive, alarmed pedestal with a can of sand. The can of sand and the red phosphorus have the exact same dimensions (length=22cm & radius=3.8).
- Calculate the mass of each cylinder (ignoring the mass of the can itself). Density of the red phosphorus=2.34 g/cm^3 and density of sand=3.00 g/cm^3).

Question

DIMENSIONAL ANALYSIS PROBLEM:
Joe employs Will to place a solid cylinder of red phosphorus that sits on a weight-sensitive, alarmed pedestal with a can of sand. The can of sand and the red phosphorus have the exact same dimensions (length=22cm & radius=3.8).
- Calculate the mass of each cylinder (ignoring the mass of the can itself). Density of the red phosphorus=2.34 g/cm^3 and density of sand=3.00 g/cm^3).

anonymous · Answer

Here's what I have so far, but I don't know if it's right :(

aaronq · Answer

not quite right. 

Using the density ($\rho$) formula, and the formula for the volume of a cylinder we get:

      $\large \sf mass=V*\rho=\pi r^2h*\rho$

Plug in the dimensions and, for each cylinder, use the appropriate density. 

All the length dimensions are in cm, there is no need for conversions.