Class 8 Chapter 16: Surface Area and Volume

# Class 8 Chapter 16: Surface Area and Volume

Important Concepts and Formulas on Surface Area and Volume

1.      Amount of space occupied by a 3D object is called its volume.

2.      For a cuboid whose length is l units, breadth is b units and height is h units,

·        Volume of a cuboid = (l × b × h) cubic units
·        Total surface area of a cuboid = 2 (l × b + b × h + h × l) sq. units
·        Lateral surface area of a cuboid or area of four walls = 2 (l + b ) × h sq. units
·        The length of the diagonal of a cuboid = sqrt(l2 + b2 + h2) units

3.      For a cube of side a units,

·        Volume of a cube = a3 cubic units
·        Total surface area of a cube = 6a2 sq. units
·        Lateral surface area of a cube = 4a2 sq. units
·        Length of the diagonal of a cube = sqrt(3) × a units

4.      For a right circular cylinder of radius r units and height h units,

·        Volume of a cylinder = πr2h cubic units
·        Curved surface area of a cylinder = 2πrh sq. units
·        Total surface area of a cylinder = 2πr(r + h) sq. units

5.      For a hollow right circular cylinder of outer radius R units and inner radius r units,

·        Curved surface area = 2πh(R + r) sq. units
·        Total surface area = 2π(R + r) (h + R – r) sq. units
·        Volume = πh(R2 – r2 ) cubic units

6.      For a right circular cone of radius r units, height h units and slant height l units,

·        Volume of a cone = 1/3 πr2h cubic units
·        Curved surface area of a cone = πrl sq. units
·        Total surface area of a cone = πr(l + r) sq. units

7.      1 cm3 = 1 mL, 1000 cm3 = 1 L, 1000000 cm3 = 1 m3 = 1 kL.