Cylinder Total Surface Area | Exercise 13.2 | Q2

Question 2: It is required to make a closed cylindrical tank of height 1 m and base diameter 140 cm from a metal sheet. How many square metres of the sheet are required for the same?

Explanatory Answer

The tank required to be made is a closed cylindrical tank. Therefore, the top of the cylindrical tank will be closed.
The area of sheet metal required to make the tank will include the base area and the area of the top. i.e., we have to compute the total surface area of the cylinder.

Total surface area of a cylinder = 2 × π × r × (h + r)
Height = 1 m
Base diameter = 140 cm. So, base radius = 70 cm
Convert base radius to m. Base radius = \\frac{70}{100}) m = \\frac{7}{10}) m

Take π =\\frac{22}{7})
Total surface area = 2 × \\frac{22}{7}) × \\frac{7}{10}) × (\\frac{7}{10}) + 1)
= \\frac{44}{10}) × \\frac{17}{10})
= \\frac{748}{100})
Or total surface area = 7.48 m²
7.48 m² of sheet metal is required to make the cylindrical tank.

Exercise 13.1 | Surface Area of Cubes & Cuboids

1. Class 9 Exercise 13.1 Question 3 | Height of hall ▶
2. Class 9 Exercise 13.1 Question 6 | TSA of Herbarium ▶
3. Class 9 Exercise 13.1 Question 7 | Shanti Sweets ▶

Exercise 13.2 | Surface Area of Cylinders

1. Class 9 Exercise 13.2 Question 3 | CSA TSA of Metal Pipe ▶
2. Class 9 Exercise 13.2 Question 4 | Roller & Playground ▶
3. Class 9 Exercise 13.2 Question 9 | Cylindrical Petrol Tank ▶
4. Class 9 Exercise 13.2 Question 10 | CSA of Decorative Lampshade ▶

Exercise 13.3 | Surface Area of Cones

1. Class 9 Exercise 13.3 Question 5 | Length of Tarpaulin 3 m wide ▶
2. Class 9 Exercise 13.3 Question 8 | Cost of painting conical barricades ▶

Exercise 13.4 | Surface Area of Spheres & Hemispheres

1. Class 9 Exercise 13.4 Question 8 | Outer CSA of hemispherical bowl ▶
2. Class 9 Exercise 13.4 Question 9 | Surface area of sphere & Cylinder ▶