1. MEASUREMENT

2. Quantities and Units A quantity is anything that can be measured.
To identify the thing that is being measured a unit of measurement is used.
In science, the accepted system of units used is the S.I. (Système International d'Unités) is used.

3. Two Types of Basic Quantities
There are two (2) types of basic or fundamental quantities used in science:
Base quantities are those quantities that are common to any object.
Derived Quantities are quantities formed by combining two or more base quantities (using multiplication or division).

4. BASE QUANTITIES Length (l) Mass (m) Time (t) Temperature (T)
Current (I)
Light Intensity
Amount of Substance

5. Derived Units Name of Quantity Formula Derived Units Area
Length x Breadth
Metre-squared ( 𝑚 2 )
Volume
Length x breadth x height
Metre-cubed ( 𝑚 3 )
Speed
Distance / Time
Metre per second ( 𝑚 𝑠 −1 )
Pressure
Force / Area
Newton per metre squared (N 𝑚 −2 )
Pascal (𝑃𝑎)

6. Prefixes Used Prefix Symbol Value Multiple Kilo Mega Giga Tera K M G T
10 3
10 6
10 9
10 12
Submultiple
Deci
Centi
Milli
Micro
Nano
pico d c m μ n p
10 −1
10 −2
10 −3
10 −6
10 −9
10 −12

7. Scientific Notation or Standard Form
Standard index form is also known as standard form. It is very useful when writing very big or very small numbers. In standard form, a number is always written as: A × 10 n A is always between 1 and 10. 𝑛 tells us how many places to move the decimal point.

8. Examples
The distance of the Earth from the Sun is 149,597,870,700 m ( million miles). Write this in scientific notation.
The diameter of an atom is m. Write this in standard form.

10. Length Metre (m) Kilometre (km) = 10 3 𝑚 Centimetre (cm) = 10 −2 𝑚
Millimetre (mm) = 10 −3 𝑚
Micrometre (micron) (μm) = 10 −6 𝑚
Nanometre (nm) = 10 −9 𝑚

11. Mass Kilogram (kg) Gram (g) = 0.001 kg
The international prototype kilogram (the inch ruler is for scale). The prototype is manufactured from a platinum–iridium alloy and is 39.17 mm in both diameter and height.

12. Measuring Mass
Beam Balance
Lever Balance
Digital Top-Pan Balance

13. TIME Second (s) Millisecond (ms) = .001 s Microsecond (μs) = .000001 s
Nanosecond (ns) =
Light year (ly)
A light-year is a unit of distance. It is the distance that light can travel in one year. Light moves at a velocity of about 300,000 kilometers (km) each second. So in one year, it can travel about 10 trillion km.

14. Vernier Scales and Micrometers
Lengths can be measured with a ruler to an accuracy of about 1 mm. Some investigations may need a more accurate measurement of length, which can be achieved by using a vernier calipers or a micrometer screw gauge.
Micrometer Screw Gauge
Vernier Caliper

15. How to use a Vernier Caliper

16. How to use a Micrometer Screw Gauge

17. Errors/Uncertainties in Measurement
Errors/uncertainties in measurement can be due to a number of factors, including:
The limitations of the measuring instrument
Variations in how the measurements are made
The conditions of the experiment
The common types of error in measurements are:
Errors due to parallax
Systematic errors

18. Parallax Error

19. Systematic Errors

20. Term Used in Experimental Physics
Range refers to the size of the interval between the maximum and minimum quantities that a measuring instrument can measure.
Sensitivity (resolution) measures the response of an instrument to the smallest change in input. The greater the response to a small change, e.g, in voltage or current, the greater the sensitivity
Accuracy is how close the experimental value is to the true value. Accuracy is improved if errors due to measuring instruments and experimental procedures are identified and their effect reduced.

21. Precision refers to how small an uncertainty the measuring instrument will give. For example, a thermometer marked at every degree will give a more precise reading than one marked at every 5 degree interval.
Linear Scale: scales where the marks are evenly spaced.
Non-linear Scales: the markings are not evenly spaced making it difficult to read between 2 points on the scale