Page 35 - Physics

Measurement

Table 2.2: Some of the vector and scalar Table 2.3 gives some of the units in
quantities comparison to the metre. Very small lengths

Vector quantities Scalar quantities are measured and expressed in mm, μm,
nm, pm or fm.
Force Mass
Displacement Distance
Acceleration Time The length of an object is measured using
Velocity Electric current specifi c instruments. The choice of an
Momentum Density instrument to be used is determined by
Magnetic fi eld Pressure the following factors:
Electric fi eld Work 1. The desired degree of precision.
energy 2. The size of the physical quantity to
power be measured.
Volume 3. The shape of the object.
Area
Table 2.3: Gives some of the units in

Measurement of Length comparison to the metre
Length is the most commonly measured Distance Comparison with
quantity in daily life. Length is used to SI unit
give the dimensions of an object or the 1 kilometre (km) 1 000 m
distance between two points. Hence, 1
distance is defi ned as the path taken by 1 centimetre (cm) 100 m
a particle in space between two points or
objects. The distance around the surface 1 millimetre (mm) 1 m
of an object is called the perimeter. You 1 000
can measure the distance ranging from 1
small to large distances such as the distance 1 micrometre (µm) 1 000 000 m
from the earth to the sun. To cope with
these differences, there are several other 1 nanometre (nm) 1 m
units obtained from the metre, namely, 1 000 000 000
kilometre (km), centimetre (cm), millimetre
(mm), micrometre (μm), nanometre (nm), Basic equipment/apparatus and
picometre (pm) and femtometre (fm). Their their uses
equivalence is as follows: The basic equipment or apparatus for
1 km = 1000 m; measurements in physics serves as an
1 m = 100 cm; essential foundation for conducting
1 cm = 10 mm; experiments and obtaining reliable data.
1 mm = 1000 μm; This equipment includes measuring
1 μm = 1000 nm; instruments such as rulers, callipers, and
1 nm = 1000 pm; micrometres, which provide accurate length
1 pm = 1000 fm.

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