This document discusses surface area and volume. It defines volume as the space occupied by a three-dimensional object. It provides formulas to calculate the volume of a cube and cuboid. Examples are given to calculate the volume of cubes and cuboids with given dimensions. Another example calculates the total surface area and lateral surface area of a cube given its volume. Further examples calculate the volume of air in a hall given the height and floor area, and the amount of air per person in an auditorium given its dimensions and number of people. Students are assigned homework to practice these types of volume and surface area calculation problems.

1. SURFACE AREA AND
VOLUME
Class -VIII

2. Volume
The capacity of a
three dimensional
object( or a solid
figure) , or the space
occupied by it is
called its volume.
length
b
h
l
l
l

3. Formulas to find volume of a cube
and cuboid
 Volume of a cuboid =length X breadth X height
 Volume of a cube =length X length X length=
(length)3

4. Problems related to volume
 Find the volume of a cube 3.5 m long.
Solution: Given: length=3.5m
To find: Volume of a cube=?
Volume of a cube =(length)3
=(3.5)3
=42.875 m3
Ans: The volume of the cube is 42.875m3

5. contd…
 Find the volume of a cuboid 7.5 cm long,5 cm wide and 4.5cm
high..
Solution: Given: l=7.5cm, b=5 cm and h=4.5 cm
To find: Volume of a cuboid=?
Volume of a cuboid =length X breadth X height
=7.5 X 5 X 4.5
=168.75 cm3
Ans: The volume of the cube is 168.75m3

6. Contd…
 If the volume of a cube is 8m3,find its total surface area and
lateral surface area.
Solution: Given: volume of a cube=8m3
To find: Total surface and lateral surface area of the
cube=?
if Volume of a cube =(length)3
(length)3=8
length=2 m.
Total surface area of cube =6 l2= 6 X 22=24 sq.m
Lateral surface area of cube =4 l2= X 22=16 sq.m

7. Contd…
 A hall is 4.5 m high and the area of the
rectangular shaped floor is 165 sq.m
Find the volume of air in the hall.
Solution : Given: height=4.5 m.
area of rectangular shaped floor =length X breadth=165 sq.m
To find: volume of air in the hall=?
 Volume of a cuboid =length X breadth X

8. Contd..
 An auditorium is 30 m long, 20 m wide and its
ceiling is 20 m above the floor. There are 18
people on stage performing in front of an
audience of 462 people. How much air is there
for each person in the auditorium?
 Hint: volume of room ÷ total no. of people in
the
room

9. Home Assignment
Revision Ex: Q. 6 ,7 ,8 and practice
the sums done in the class.

10. Activity..
1) 1 cm3= ____________ mm3
2) 1 dm3= ____________cm3 =_____
mm3
3) 1 m3= ____________ cm3
4) 1 dcm3= ____________ m3