1. MEASUREMENTS
Key notes:
1. The S.I unit for length is metre (m); for mass is kilogram (kg) and for time is
seconds (s).
2. When using a ruler, try to avoid parallex and end errors.
3. The ruler can be read up to 1 decimal place in cm, e.g. 4.3cm.
4. The jaws of the vernier callipers enable us to measure the interval or external
diameter of an object accurately.
5. The vernier callipers can be read up to 2 decimal places in cm, e.g. 2.34cm. A
ruler can be read up to only 1 decimal place in cm, e.g. 2.3cm.
6. When reading the vernier callipers, (e.g. 2.34cm) 2.3cm is read from the main
scale. 0.04cm is read from the vernier scale.
7. A micrometer screw gauge may be used to measure lengths less than 4cm. For
length of 1cm to 10cm, the vernier callipers may be used. To measure length
greater than 10cm, a metre rule is suitable.
8. The mass of an object is the amount of matter it contains.
9. The mass of an object is constant.
10. The period of oscillation of a simple pendulum increases as its length
increases, but is independent of the amplitude of the oscillation and the mass
of its bob.
11. Units for density : kg/m³ or g/cm³
12. 1 g/cm³ = 1000 kg/m³
Formulas:
The Simple Pendulum
Frequency, f = one second / period
= 1 / T
Density, ρ = mass / volume
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