Formula for a sphere

HEMISPHERE A plane through the centre of a sphere cuts it into two equal parts. Each part is called a hemisphere.

FORMULAE For a hemisphere of radius r, we have

• Volume of the hemisphere cubic units
• Curved surface area of the hemisphere = (2πr2) sq units
• Total surface area of the hemisphere = (3πr2) sq units

SOLVED EXAMPLES

question A sphere of radius 5 cm. find its volume and surface area

 Sol.   Here, r = 5cm

So, volume of Sphere is cubic units

    =

    = 523.80 cm3

Surface area of sphere is = sq units

    = 4×3.14×5×5

    = 62.8 cm2

question How many spherical bullets can be made out of a solid cube of lead whose edge measures 44 cm, each bullet being 4 cm in diameter?

Sol. Length of each edge of the cube = 44 cm

Volume of the cube = (44 × 44 × 44) cm3

Radius of each bullet, r = 2 cm

Volume of each bullet

Number of bullets formed

Hence, the number of bullets formed is 2541.

CBSE NCERT Solutions for Class 8 Maths

class 8 maths NCERT solutions Chapter 1: Rational Numbers

class 8 maths NCERT solutions  Chapter 2: Linear Equations in One Variable

class 8 maths NCERT solutions  Chapter 3: Understanding Quadrilaterals

class 8 maths NCERT solutions Chapter 4: Practical Geometry

class 8 maths NCERT solutions  Chapter 5: Data Handling

class 8 maths NCERT solutions  Chapter 6: Square and Square Roots

class 8 maths NCERT solutions  Chapter 7: Cube and Cube Roots

class 8 maths NCERT solutions  Chapter 8: Comparing Quantities

NCERT Class 8 Maths solution Chapter 9: Algebraic Expressions and Identities

class 8 maths NCERT solutions  Chapter 10: Visualizing Solid Shapes

class 8 maths NCERT solutions Chapter 11: Mensuration

class 8 maths NCERT solutions  Chapter 12: Exponents and Powers

class 8 maths NCERT solutions  Chapter 13: Direct and Inverse Proportions

class 8 maths NCERT solutions  Chapter 14: Factorization

class 8 maths NCERT solutions  Chapter 15: Introduction to Graphs

class 8 maths NCERT solutions  Chapter 16: Playing with Numbers

Notes,worksheet and solved question for Maths class 8 

1.  class 8 maths notes on chapter Liner equation in one variable
2. class 8 maths notes on chapter algebric expression 
3. class 8 maths notes on chapter Mensuration 
4. class 8 maths notes on chapter Square and square roots 
5. class 8 maths notes on chapter statistice
6. class 8 maths notes on chapter practical Geometry
7. class 8 maths notes on chapter commericial maths
8. class 8 maths notes on chapter solid shape
9. class 8 maths notes on chapter quadrilaterals
10. class 8 maths notes on chapter exponents
11. class 8 maths notes on chapter factorisation 
12. class 8 maths notes on chapter inverse proporation 
13. class 8 maths notes on chapter cube and cube roots 

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chapter wise online test for class 8 maths