Math Problem Statement

Solve both

Solve the problem of finding the volume of a piece of wood and the height of a cone with given parameters.

Solution

Let me analyze the image and solve the problems step-by-step.


First Problem:

We are tasked to find the volume of the piece of wood, where the central cone is cut out of a cylinder.

Given:

  • Cylinder:
    • Radius r=6cmr = 6 \, \text{cm}
    • Height h=12cmh = 12 \, \text{cm}
  • Cone:
    • Radius r=6cmr = 6 \, \text{cm} (same as the cylinder's radius)
    • Height h=12cmh = 12 \, \text{cm} (same as the cylinder's height)

Step 1: Calculate the volume of the cylinder:

The volume of a cylinder is given by: Vcylinder=πr2hV_{\text{cylinder}} = \pi r^2 h Substitute r=6r = 6 and h=12h = 12: Vcylinder=π(6)2(12)=π(36)(12)=432πcm3V_{\text{cylinder}} = \pi (6)^2 (12) = \pi (36)(12) = 432\pi \, \text{cm}^3

Step 2: Calculate the volume of the cone:

The volume of a cone is given by: Vcone=13πr2hV_{\text{cone}} = \frac{1}{3} \pi r^2 h Substitute r=6r = 6 and h=12h = 12: Vcone=13π(6)2(12)=13π(36)(12)=144πcm3V_{\text{cone}} = \frac{1}{3} \pi (6)^2 (12) = \frac{1}{3} \pi (36)(12) = 144\pi \, \text{cm}^3

Step 3: Subtract the cone's volume from the cylinder's volume:

Vwood=VcylinderVconeV_{\text{wood}} = V_{\text{cylinder}} - V_{\text{cone}} Vwood=432π144π=288πcm3V_{\text{wood}} = 432\pi - 144\pi = 288\pi \, \text{cm}^3

Final Answer (approximation):

Vwood=288π904cm3(rounded to the nearest whole number).V_{\text{wood}} = 288\pi \approx 904 \, \text{cm}^3 \, \text{(rounded to the nearest whole number)}.


Second Problem:

A cylinder and a cone have the same volume. We need to find the height of the cone.

Given:

  • Cylinder:
    • Radius r=2inchesr = 2 \, \text{inches}
    • Height h=27inchesh = 27 \, \text{inches}
  • Cone:
    • Radius r=3inchesr = 3 \, \text{inches}
    • Height h(to be determined)h \, \text{(to be determined)}

Step 1: Find the volume of the cylinder:

The volume of a cylinder is given by: Vcylinder=πr2hV_{\text{cylinder}} = \pi r^2 h Substitute r=2r = 2 and h=27h = 27: Vcylinder=π(2)2(27)=π(4)(27)=108πin3V_{\text{cylinder}} = \pi (2)^2 (27) = \pi (4)(27) = 108\pi \, \text{in}^3

Step 2: Set the cone's volume equal to the cylinder's volume:

The volume of a cone is: Vcone=13πr2hV_{\text{cone}} = \frac{1}{3} \pi r^2 h Substitute r=3r = 3 and equate it to 108π108\pi: 13π(3)2h=108π\frac{1}{3} \pi (3)^2 h = 108\pi 13π(9)h=108π\frac{1}{3} \pi (9) h = 108\pi 3h=1083h = 108 h=1083=36inchesh = \frac{108}{3} = 36 \, \text{inches}

Final Answer:

The height of the cone is: h=36inches.h = 36 \, \text{inches}.


Summary of Answers:

  1. Volume of the piece of wood: 904cm3904 \, \text{cm}^3 (rounded to the nearest whole number).
  2. Height of the cone: 36inches36 \, \text{inches}.

Do you have any questions or need further clarification?


5 Relative Questions:

  1. How do you calculate the volume of a cylinder?
  2. What is the difference in formula between the volume of a cylinder and a cone?
  3. Why is the volume of a cone one-third that of a cylinder with the same base and height?
  4. How does changing the radius affect the volume of a cone or cylinder?
  5. What are real-world applications of calculating volumes of solids?

One Tip:

Always ensure units are consistent throughout a calculation; converting units when needed helps avoid mistakes!

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Math Problem Analysis

Mathematical Concepts

Geometry
Volume of Solids

Formulas

Volume of a cylinder: V = πr²h
Volume of a cone: V = (1/3)πr²h

Theorems

Relationship between cylinder and cone volumes

Suitable Grade Level

Grades 8-10