NCERT Class 9 Solutions: Surface Areas and Volumes (Chapter 13) Exercise 13.2 – Part 2

Different types of shapes also its volume and total surface area formulas

Different Types of Shapes

Different types of shapes also its volume and total surface area formulas

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

  • The roller length is (h) Equation

  • The cylinder radius is Equation

  • Total no. of revolutions Equation

    Distance covered by roller in one revolution Equation

    • Equation

    • Equation Equation

    • Equation

Area of the playground

  • Equation ( Equation complete revolutions to level a playground)

  • Equation

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

  • The pillar radius Equation

  • The pillar height Equation

  • Painting rate Equation

    Curved surface

    • Equation

    • Equation

    • Equation

    Total cost of painting

  • Equation (Painting rate Equation )

  • Equation

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

  • The radius of the base r and the height of the cylinder h.

  • Area of a right circular cylinder is Equation

Curved surface area

  • Equation

  • Equation Equation

  • Equation

  • Equation

  • Equation

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

  1. Its inner curved surface area,

  2. The cost of plastering this curved surface at the rate of Equation

Solution:

Circular well radius Equation The well depth Equation Plastering rate Equation

  1. Curved surface

    • Equation

    • Equation

    • Equation

  2. Cost of plastering = Equation

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

Formulas for surface area and volume of a cylinder

Surface Area and Volume of a Cylinder

Formulas for surface area and volume of a cylinder

  • The pipe radius Equation

  • The pipe length Equation

Total radial surface or curved surface area of the pipe

  • Equation

  • Equation

  • Equation

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