Math Problem Statement

A cylinder with base radius of 8 cm and height of 2 cm is melted to form a cone of height 6 cm. The radius of the cone is:

Solution

To solve this problem, we will use the concept of volume conservation since the material of the cylinder is melted to form a cone.

Step 1: Volume of the Cylinder

The formula for the volume of a cylinder is:

Vcylinder=πr2hV_{\text{cylinder}} = \pi r^2 h

Here:

  • Base radius of the cylinder r=8cmr = 8 \, \text{cm}
  • Height of the cylinder h=2cmh = 2 \, \text{cm}

Vcylinder=π(8)2(2)=π642=128πcm3V_{\text{cylinder}} = \pi (8)^2 (2) = \pi \cdot 64 \cdot 2 = 128 \pi \, \text{cm}^3

Step 2: Volume of the Cone

The formula for the volume of a cone is:

Vcone=13πR2HV_{\text{cone}} = \frac{1}{3} \pi R^2 H

Here:

  • Height of the cone H=6cmH = 6 \, \text{cm}
  • Radius of the cone RR (to be determined)

Equating the volumes of the cylinder and cone:

128π=13πR2(6)128 \pi = \frac{1}{3} \pi R^2 (6)

Cancel π\pi from both sides:

128=2R2128 = 2 R^2

Step 3: Solve for RR

R2=1282=64R^2 = \frac{128}{2} = 64

R=64=8cmR = \sqrt{64} = 8 \, \text{cm}

Final Answer:

The radius of the cone is 8 cm.

Would you like further details or explanations? Here are related questions for deeper understanding:

  1. How does volume conservation help in solving such problems?
  2. What are the key differences between the formulas for the volume of a cylinder and a cone?
  3. How would the result change if the height of the cone were doubled?
  4. Can this method be extended to irregular shapes?
  5. Why is the factor 13\frac{1}{3} present in the cone volume formula?

Tip: Always ensure units are consistent when working with volume problems!

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Math Problem Analysis

Mathematical Concepts

Volume Conservation
Cylinders
Cones
Geometry

Formulas

Volume of a cylinder: V = πr^2h
Volume of a cone: V = (1/3)πR^2H

Theorems

Volume conservation principle

Suitable Grade Level

Grades 8-10