NCERT Class 9 Solutions: Surface Areas and Volumes (Chapter 13) Exercise 13.2 – Part 2 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Different Types of Shapes Also Its Volume and Total Surface …

Q-4 The diameter of a roller is and its length is . It takes complete revolutions to move once over to level a playground. Find the area of the playground in . Solution:

  • The roller length is (h)
  • The cylinder radius is
  • Total no. of revolutions
    • Distance covered by roller in one revolution
  • Area of the playground
  • ( complete revolutions to level a playground)

Q-5 A cylindrical pillar is in diameter and in height. Find the cost of painting the curved surface of the pillar at the rate of . Solution:

  • The pillar radius
  • The pillar height
  • Painting rate
    • Curved surface
    • Total cost of painting
      • (Painting rate )

Q-6 Curved surface area of a right circular cylinder is . If the radius of the base of the cylinder is , find its height. Solution:

  • The radius of the base r and the height of the cylinder h.
  • Area of a right circular cylinder is

Curved surface area

Q-7 The inner diameter of a circular well is . It is deep. Find

  1. Its inner curved surface area,
  2. The cost of plastering this curved surface at the rate of

Solution:

Circular well radius The well depth Plastering rate

  • Curved surface
  • Cost of plastering =

Q-8 In a hot water heating system, there is a cylindrical pipe of length and diameter . Find the total radiating surface in the system. Solution:

Formulas for Surface Area and Volume of a Cylinder
  • The pipe radius
  • The pipe length

Total radial surface or curved surface area of the pipe