Chapter 1 Physical Quantities, Units and Measurements

Value of Physical Quantities

Quantity = Numerical Magnitude + Unit

7 Base Units

Length, Mass, Time, Electric Current, Thermodynamic Temperature, Luminous Intensity, Amount of Substance

Length

metre (m)

Mass

kilogram (kg)

Time

second (s)

Electric Current

ampere (A)

Thermodynamic Temperature

kelvin (K)

Luminous Intensity

candela (cd)

Amount of Substance

mole (mol)

Prefixes

Used to represent powers of 10

tera (T)

10¹²

giga (G)

10⁹

mega (M)

10⁶

kilo (k)

10³

deci (d)

10⁻¹

centi (c)

10⁻²

milli (m)

10⁻³

micro (µ)

10⁻⁶

nano (n)

10⁻⁹

Diameter of Typical Atom

10⁻¹⁰ m

Types of Physical Quantities

Scalars and Vectors

Scalars

Have only magnitude

Vectors

Have magnitude and direction

Example of Scalar

Speed

Example of Vector

Velocity

Numerical Representation of Vectors

If motion is in one line, use ± symbols to represent direction. We must write in the direction that is positive or negative.

Graphical Representation of Vectors

Use arrows to represent a vector. The direction of the arrow is the same as the vector. The length represents the magnitude of the vector if drawn to scale.

Result of Addition of Vectors

resultant

Vectors upon the same line

5N - (2N+3N) = 0N

Vectors not upon the same line

Write the scale (1u:1u)
Draw a reference line (Vertical or Horizontal)
Choose a starting point on the reference line
Draw a straight line from the start point to end point and that will be the answer (Pink Line)