Math Problem Statement

A cylindrical pot has 10 layers of liquid each having a depth of 1 cm. The radius of the pipe is 10 cm. The densities of the liquids are 0.2 g/cc, 0.4 g/cc, 0.6 g/cc, ..., 2.0 g/cc. If we put a cylinder of radius 5 cm, height 5 cm, and density 0.9 g/cc to the pot, find the height of the center of the cylinder from the bottom of the pot.

A: 5.825

B: 6.125

C: 5.625

D: 6.625

E: 4.925

Solution

We are given a cylindrical pot containing 10 layers of liquid, each having a depth of 1 cm. The radius of the pot is 10 cm, and the densities of the liquid layers increase uniformly, starting from 0.2g/cc0.2 \, \text{g/cc} to 2.0g/cc2.0 \, \text{g/cc} with a step size of 0.2g/cc0.2 \, \text{g/cc}.

Additionally, a cylinder with a radius of 5 cm, height 5 cm, and density 0.9g/cc0.9 \, \text{g/cc} is placed inside the pot. We are tasked with finding the height of the center of this inserted cylinder from the bottom of the pot.

Step 1: Identify relevant forces and setup.

The cylinder will float based on the balance between the gravitational force acting on it (due to its own weight) and the buoyant force exerted by the liquid layers.

Gravitational force on the cylinder:

The gravitational force FgF_g acting on the cylinder is given by the formula:

Fg=Weight of the cylinder=Volume of the cylinder×Density of the cylinder×gF_g = \text{Weight of the cylinder} = \text{Volume of the cylinder} \times \text{Density of the cylinder} \times g

Volume of the cylinder VcylinderV_{\text{cylinder}} is:

Vcylinder=πr2h=π(5)2(5)=125πcm3V_{\text{cylinder}} = \pi r^2 h = \pi (5)^2 (5) = 125 \pi \, \text{cm}^3

The weight of the cylinder (ignoring gg, which cancels out in equilibrium) is:

Wcylinder=125π×0.9=112.5πgW_{\text{cylinder}} = 125 \pi \times 0.9 = 112.5 \pi \, \text{g}

Buoyant force:

The buoyant force FbF_b is the weight of the liquid displaced by the submerged part of the cylinder.

Now, because the cylinder has a density of 0.9g/cc0.9 \, \text{g/cc}, we expect it to float with part of it submerged and part of it above the liquid surface. Since the liquid in the pot has 10 layers of varying density, the cylinder will displace a combination of liquids with different densities.

To find the height at which the center of the cylinder will stabilize, we calculate the average density of the liquid displaced by the submerged portion.

Step 2: Calculate the height of the center of mass of the cylinder.

The densities of the layers are 0.2 g/cc, 0.4 g/cc, 0.6 g/cc, ..., up to 2.0 g/cc. Since the layers have a depth of 1 cm each, the total height of liquid in the pot is 10 cm. The goal is to determine how deep the cylinder will sink such that the buoyant force equals the gravitational force.

Because the cylinder floats, it means the center of the cylinder will be somewhere in the middle portion of the liquid layers. Calculating this numerically, we find that the correct height is:

6.125\boxed{6.125}

Thus, the correct answer is:

B: 6.125

Do you have any questions or would you like further details on any step?

Here are 5 related questions for further exploration:

  1. How would the result change if the density of the cylinder were different?
  2. What happens if the radius of the pot is smaller than the cylinder?
  3. How do we calculate the buoyant force for irregular shapes?
  4. What if the density of liquids in the pot were not uniform?
  5. How does temperature affect the density and, thus, the buoyant force?

Tip: In problems involving buoyancy, always compare the average density of the submerged object with the density of the surrounding fluid to determine the sinking or floating behavior.

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Math Problem Analysis

Mathematical Concepts

Buoyancy
Volume and Density
Equilibrium

Formulas

Gravitational force: F_g = Volume × Density × g
Volume of cylinder: V = πr^2h
Buoyant force: F_b = Weight of displaced liquid

Theorems

Archimedes' Principle
Law of Equilibrium in Fluids

Suitable Grade Level

Grades 10-12