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Problem With Cylinder Involving Mass and Volume 
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#1
Aug3012, 06:51 PM

P: 1

1. The problem statement, all variables and given/known data
There is a cylinder with two sections (not straight down the middle). One has density 4.5(g/cm^3) the other with 6.4. The radius of the cylinder is 6cm and the total length is 19cm. The total mass is 11833 grams. I need to find the length of the lighter density section of the cylinder. 2. Relevant equations A of circle = pi*r^2 V = B*h D = m/v 3. The attempt at a solution I could easily solve this problem if I knew the steps to take. The total volume is about 113 cm^3, but I don't see how I can apply that information. Also, am I correct in thinking that densities cannot be combined? Sorry for the measly attempt, it is just that I am unable to find a way to solve this. The math should be easy. I just need a plan. 


#2
Aug3012, 09:11 PM

P: 3,151

You can write plenty of equations. For example write equations for ...
1) The mass of the low density part M_{LD} as a function of it's unknown length L_{LD} 2) The mass of the high density part M_{HD} as a function of it's unknown length L_{HD} You can also write v.simple equations such as ones for.. 3) The total mass M_{TOT}as a function of M_{LD} and M_{HD} 4) The total Length L_{TOT} as a function of L_{LD} and L_{HD} Then you will have lots of equations and some unknowns. Solve. 


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