Measurement
Chapter 37
Length-- Measured in cm, m,
km.
• Use a meter stick or a
ruler to measure the
length of a straight
line.
• An opisometer can be
used to measure the
length of a curved line
• A Vernier callipers
can be used to measure
the internal and
external diameters of
cylinders.
opisometer
Trundle wheel
Area—measured in
2
cm ,
2
m,
• The area of a rectangle = length by breadth.
• Area of circle = π r2.
To find the area of an irregular shape—use graph
paper.
Volume—measured in
3
cm ,
3
m.
• The volume of an object is the amount of
space it takes up.
• The volume of a rectangular block =
(Length x Breadth x Height)
Volume of a Liquid
• The volume of
a liquid is
found by
pouring it into
a measuring
(graduated)
cylinder.
Volume of a small object
• The graduated cylinder can also be used to measure the
volume of an object. If you place it in the cylinder and
you measure how much the water goes up by. This is
the same volume as the volume of the object.
What is the volume of
the small Stone?
Answer:
10cm3 - 8cm3 = 2cm3
Volume of a large object
• To find the volume of a large irregular
shaped object—use an overflow can.
• If the object is too big to fit into a
graduated cylinder, place it in an overflow
can which is filled to the brim with water.
The object pushes out a volume of water
equal to its own volume.
What is the volume of the large
stone?
Answer:
• The
volume of
the large
stone is
14cm3.
Mass
• The mass of an
object is the
amount of
matter in the
object.
• To measure the
mass of an
object we use a
balance.
What is the mass of the stone?
Ans:
34.67 grams
Time—measured in s, min, hrs
• Use a watch to tell the time.
• Time is measured in seconds, minutes, and
hours.
How many seconds are in a minute?
60 sec in a minute
How many minutes are in an hour?
60 minutes in an hour
How many hours are in a day?
24 hours in a day