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Question

A square sheet of side length 44 cm is rolled along one of its sides to form a cylinder by making opposite edges just to touch each other. What is the volume of the cylinder ? (Take π = 22/7)  

This question was previously asked in
CDS I 2023 English Previous Year Paper (16-April-2023)
The correct answer is

6776 cubic cm  

Calculating Volume of a Cylinder from a Square Sheet

This problem involves visualizing how a two-dimensional shape (a square sheet) is transformed into a three-dimensional shape (a cylinder) and then calculating its volume.

Understanding the Problem Transformation

We are given a square sheet with a side length of 44 cm. When this sheet is rolled along one of its sides so that opposite edges touch, it forms a cylinder. Let's see how the dimensions of the square relate to the dimensions of the resulting cylinder:

  • One side of the square becomes the height of the cylinder.
  • The other side of the square becomes the circumference of the base circle of the cylinder.

In this case, the side length of the square is 44 cm. So:

  • Height of the cylinder (h) = 44 cm
  • Circumference of the base of the cylinder (C) = 44 cm

We need to find the volume of this cylinder. The formula for the volume of a cylinder is \(V = \pi r^2 h\), where \(r\) is the radius of the base and \(h\) is the height. We are given \(h = 44\) cm and we need to find \(r\). We can find \(r\) using the circumference.

Finding the Radius of the Cylinder Base

The circumference of a circle is given by the formula \(C = 2\pi r\). We know the circumference is 44 cm and we are asked to use \( \pi = 22/7 \). Let's plug these values into the formula to find the radius \(r\).

Given:

  • Circumference \(C = 44\) cm
  • \( \pi = 22/7 \)

Formula:

\( C = 2\pi r \)

Substitute the given values:

\( 44 = 2 \times \left(\frac{22}{7}\right) \times r \)

\( 44 = \frac{44}{7} \times r \)

Now, solve for \(r\):

\( r = 44 \times \frac{7}{44} \)

\( r = 7 \) cm

So, the radius of the base of the cylinder is 7 cm.

Calculating the Volume of the Cylinder

Now that we have the radius \(r = 7\) cm and the height \(h = 44\) cm, we can calculate the volume of the cylinder using the formula \(V = \pi r^2 h\). We will use \( \pi = 22/7 \).

Given:

  • Radius \(r = 7\) cm
  • Height \(h = 44\) cm
  • \( \pi = 22/7 \)

Formula:

\( V = \pi r^2 h \)

Substitute the values:

\( V = \frac{22}{7} \times (7)^2 \times 44 \)

\( V = \frac{22}{7} \times 49 \times 44 \)

We can cancel out the 7 in the denominator with one of the 7s from \(49 = 7 \times 7\):

\( V = 22 \times \frac{49}{7} \times 44 \)

\( V = 22 \times 7 \times 44 \)

Now, perform the multiplication:

\( V = 154 \times 44 \)

Let's do the multiplication:

  154
x  44
-----
  616  (154 * 4)
 6160  (154 * 40)
-----
 6776

\( V = 6776 \) cubic cm

The volume of the cylinder is 6776 cubic cm.

Summary of Calculations

Dimension/Property Value Calculation Method
Square Side Length 44 cm Given
Cylinder Height (h) 44 cm Side length used for rolling
Cylinder Base Circumference (C) 44 cm Other side length of the square
Cylinder Base Radius (r) 7 cm \( C = 2\pi r \Rightarrow 44 = 2 \times \frac{22}{7} \times r \)
Cylinder Volume (V) 6776 cubic cm \( V = \pi r^2 h = \frac{22}{7} \times 7^2 \times 44 \)

The calculated volume of the cylinder is 6776 cubic cm.

Revision Table: Geometry Formulas

Shape Property Formula
Square Side Length s
Circle Circumference (C) \( 2\pi r \)
Circle Area (A) \( \pi r^2 \)
Cylinder Volume (V) \( \pi r^2 h \)
Cylinder Curved Surface Area \( 2\pi r h \)
Cylinder Total Surface Area \( 2\pi r (r + h) \)

Additional Information: Rolling Shapes

When a 2D shape like a rectangle or a square is rolled to form a 3D shape like a cylinder:

  • One dimension of the 2D shape becomes the height of the cylinder.
  • The other dimension of the 2D shape becomes the circumference of the cylinder's base.
  • If you roll a rectangle along its length, the length becomes the circumference and the width becomes the height.
  • If you roll a rectangle along its width, the width becomes the circumference and the length becomes the height.
  • In the case of a square, both sides are equal. The side along which it's rolled determines which side becomes the height and which becomes the circumference. The problem states it's rolled along "one of its sides," meaning one side forms the height and the other equal side forms the circumference.
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Similar Questions

  1. A cone and a hemisphere have equal bases and volumes. What is the ratio of the height of the cone to the radius of the hemisphere?

  2. The volume of a hemisphere is 155232 cm 3. What is the radius of the hemisphere?

  3. The radius and height of a right circular cone are in the ratio 3 : 7. If the volume of the cone is 528 cm 3, then what is the height of the cone? \(\left( {{\rm{Take}}\,\,{\rm{\pi }}\,{\rm{ = }}\frac{{22}}{7}} \right)\)

  4. The length, breadth and height of a cuboid are in the ratio 27 : 8 : 1. The cuboid is melted and recast into a cube. If p is the surface area of the cuboid and q is the surface area of the cube, then what is p/q equal to?

  5. A lamp shade is in the shape of a part of a cone and its top and bottom ends are circles whose circumferences are respectively 30 cm and 40 cm. The perpendicular distance between the ends is 6 cm. If the cone were to be completed, then how far would its vertex be from the top end?

  6. Three solid lead spheres of radius 6 cm, 8 cm and 10 cm are melted together and recast as a solid sphere. What is the percentage diminution of the surface area as compared to the sum of the surface areas of the three spheres ?

  7. A solid sphere of radius 3 cm is melted to form a hollow cylinder of height 4 cm and external diameter 10 cm. What is the thickness of the cylinder?

  8. A cylindrical pipe has inner diameter of 14 cm. Water flows through it at a rate of 154 litres per minute. What is the speed of water in km/hr? \(\left( {{\rm{Take}}\,\,{\rm{\pi }}\,{\rm{ = }}\frac{{22}}{7}} \right)\)

  9. What is the radius of the base of the cone ?

  10. A cone of height 16 cm and diameter 14 cm is mounted on a hemisphere of same diameter. What is the volume of the solid thus formed? (take π = 22/7)


Important Questions from Solid Figures

  1. If 3.96 cubic dm of lead is to be drawn in to a cylindrical wire of diameter 0.6 cm, then the length of the wire (in metres), is:

  2. A cone and a hemisphere have equal bases and volumes. What is the ratio of the height of the cone to the radius of the hemisphere?

  3. A metallic solid cuboid of dimensions 36 cm × 18 cm × 12 cm is melted and recast in the form of cubes of side 6 cm. Find the number of cubes so formed.

  4. A solid cylinder has a radius of 9 cm and a height of 25 cm. What is the ratio of its total surface area to its curved surface area?

  5. If the surface area of a sphere is 64 π cm 2, then the volume of the sphere is:

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