The core principle is that the volume of the material remains constant when a solid is melted and recast. Therefore, the volume of the copper sphere is equal to the volume of the wire (which is a cylinder).
\(V_s = \frac{4}{3} \pi r_s^3\)
\(V_s = \frac{4}{3} \pi (3 \text{ cm})^3 = \frac{4}{3} \pi (27 \text{ cm}^3) = 36 \pi \text{ cm}^3\)
\(V_w = \pi r_w^2 h\)
where '\(h\)' is the length of the wire.\(V_w = \pi (0.25 \text{ cm})^2 h = \pi (0.0625 \text{ cm}^2) h\)
\(V_s = V_w\)
\(36 \pi \text{ cm}^3 = \pi (0.0625 \text{ cm}^2) h\)
\(36 \text{ cm}^3 = 0.0625 \text{ cm}^2 \times h\)
\(h = \frac{36 \text{ cm}^3}{0.0625 \text{ cm}^2}\)
\(h = 576 \text{ cm}\)
\(h = \frac{576}{100} \text{ m} = 5.76 \text{ m}\)
The length of the wire is 5.76 m.
A room is L m long, B m wide and H m high. Further, L > B > H and L, B and H are integers. The length of the longest pole that can be placed in the room is 17 m and the length of the longest pole that can be placed on the floor is 15 m. What is the volume of the room?
A reservoir is in the form of a cuboid. Its length is 30 m. If 24 kL of water is removed from the reservoir, the water level goes down by 20 cm. What is the width of the reservoir?
A well is dug with a diameter of 3.5 m and 16 m depth. The earth soil so excavated is spread in the form of a right circular cone of radius 7 m. What is the height of the cone?
A tall cylindrical reservoir kept vertically is 20 m in diameter. Water is poured into it at the rate of 264 m³ per hour. What is the rate at which the water level rises in the reservoir per minute? (Take π = 22/7)
A thin metallic sheet, 1.92 m² in area, is cut into two equal pieces. One piece is used to make a hollow cube of volume P (in m³) and the other is used to make a hollow cuboid of volume Q (in m³) with dimensions in the ratio \(4:2:1\). If no sheet is wasted, which one of the following is correct?
How many square metres of canvas (approximately) will be required to make a conical tent 3 m high so that a man 2 m tall may stand anywhere within a radius of 1 m from its centre without stooping?
N number of cubes each of side length equal to 10 cm are joined end to end in a row. If the total surface area of the resulting cuboid is \(3800\text{ cm}^2\), then what is the value of N?
A spherical metal ball is molten and made into n smaller identical spheres. In this process, the surface area of the smaller balls increases by 900%. What is the value of n?
Find the total surface area of a closed cylinder having a base radius of 70 m and a height of 110 m. [Use π = \(22\over7\)]
The diameter of the base and slant height of a right circular cone are 30 cm and 113 cm, respectively. Find the volume (in cm³) of the given cone.
(Use $\pi = \frac{22}{7}$)