Page 37 - Physics

Measurement

a it is also ideal for measuring
curved surfaces, large distances,
and irregular shapes where rigid
rules might be ineffective.

Figure 2.2: Tape measures Figure 2.3: Reading from a metre rule
Care should be taken while using a metre rule so as
Task 2.1 to avoid damaging the ends. This is because the rule
1. If asked to measure the length does not have an allowance (a short ungraduated
of a field, which type of portion) for wear at both ends. Suppose, you wish
instrument will you use? Why? to measure the length of a table. The zero (0 cm)
2. Place the following objects mark of the metre rule is aligned with one end of
on the paper a pencil, a book the table, as shown in Figure 2.4.

and a matchstick. Mark the
end points of each. Draw the
line-segment connecting the
points. Find the length of
each object by measuring the
distance between the points.

Figure 2.4: Measuring the length of a table
When taking a measurement, always
ensure that your eye is perpendicular Since the metre rule does not extend beyond the
to the mark on the scale of the metre end of the table, carefully mark the point on the
rule, as demonstrated in Figure 2.3, table that corresponds to the end of the metre and
otherwise the value will have an then continue, as shown in Figure 2.5.
error. An error caused by wrong
positioning of the eye is known as
parallax error. Such an error occurs
when the measurement of the length
an object is more or less than the
true length, because of the eye
being positioned at an angle to the
measurement mark. Figure 2.5: Reading to complete the length of the table

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Physics Form 1 Final.indd 31 16/10/2024 20:55