Surface Areas and Volumes in Mathematics
Updated on June 1, 2025 | By Learnzy Academy
Surface Areas and Volumesis a fundamental topic in geometry that deals with measuring the external and internal space of 3D (three-dimensional) shapes.
Surface Area refers to the total area that the surface of a 3D object occupies. It is usually measured in square units (e.g., cm², m²). Surface areas are calculated differently based on the shape of the object, such as cubes, cuboids, cylinders, spheres, cones, and hemispheres.
Volume is the amount of space enclosed within a 3D object. It is measured in cubic units (e.g., cm³, m³). Volume calculations help determine how much material or space an object can contain.
Understanding surface area and volume is essential in real-life applications such as packaging, construction, manufacturing, and fluid storage.
Common Formulas:
- Cube:
- Surface Area = 6a²
- Volume = a³
- Cuboid:
- Surface Area = 2(lb + bh + hl)
- Volume = l × b × h
- Cylinder:
- Surface Area = 2πr(h + r)
- Volume = πr²h
- Sphere:
- Surface Area = 4πr²
- Volume = (4/3)πr³
- Cone:
- Surface Area = πr(l + r)
- Volume = (1/3)πr²h
- Hemisphere:
- Surface Area = 3πr²
- Volume = (2/3)πr³
Surface Areas and Volumes
List of question on "Surface Areas and Volumes"
- Three cubes of a metal whose edges are in the ratio 3:4:5 are melted and converted into a single cube whose diagonal is 12 3 cm. Find the edges of the three cubes.
- A canal is 300 cm wide and 120 cm deep. The water in the canal is flowing with a speed of 20 km/h. How much area will it irrigate in 20 minutes if 8 cm of standing water is desired?
- A solid metallic sphere of radius 10.5 cm is melted and recast into a number of smaller cones, each of radius 3.5 cm and height 3 cm. Find the number of cones so formed.
- A cone of maximum size is carved out from a cube of edge 14 cm. Find the surface area of the cone and of the remaining solid left out after the cone carved out.
- The capacity of a cylindrical tank is 6160 cm³. Its base diameter is 28 m. What is the depth of this tank?
- A river 3 meters deep and 40 meters wide is flowing at the rate of 2 km per hour. How much water will fall into the sea in a minute?
- A cylindrical pillar has a diameter of 50 cm and a height of 3.5 m. What is the cost of painting its curved surface at the rate of Rs. 12.50 per m²?
- The diameter of a roller is 84 cm, and its length is 120 cm. It takes 500 complete revolutions to move once over and level a playground. What is the area of the playground in m²?
- A metal pipe is 77 cm long. The inner diameter of its cross-section is 4 cm and the outer diameter is 4.4 cm. What is its inner curved surface area?
- Two cubes each of edge 12 cm are joined end to end. What is the surface area of the new cuboid formed?
- The perimeter of floor of rectangular hall is 250m. The cost of the white washing its four walls is Rs. 15000. The height of the room is
- The length, breadth and height of a room is 5m, 4m and 3m. The cost of white washing its four walls at the rate of Rs. 7.50 per square meter is