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EXERCISE 1 : Unit and Dimensions

Dimensions are physical quantities which can be measured, whereas units are arbitrary names that’s correlate
to particular dimensions to make it relative (e.g., a dimension is height, whereas a meter is a relative unit that
relate to height).Seven base dimensions that can be combined to describe all of the other dimensions of interest
in engineering and physics, among other disciplines.
Conversions between British &metric system of Units
The imperial system is based on the convention of measuring based on the human form, whereas the metric
system is based on the definition of metre. The metric & imperial systems are different based on their origin, units
of measurement, and countries of use.
Conversion between Metric System and English System Units

1 inch = 2.54 cm. 1 ft = 30.48 cm. 1 mile = 1.609 km. 1 pound = 0.454 kg.
Also length: Kilometer to mile by multiplying by 5/8, e.g. 40km =25 miles. Centimetre to inch by dividing by 2.5,
e.g. 5 cm = 2 inches, 30 cm = 12 inches = 1 ft.

Fundamental and derived units in SI System
The SI system’s basic units are the units of fundamental physical quantities which are not produced from other
SI units. It is called a derived unit when derived quantities are expressed in the same unit. The meter, kilogram,
ampere and second are the 7 fundamental and derived units in physics.
Derived SI Units
• Length - meter (m)
• Time - second (s)

• Amount of substance - mole (mole)
• Electric current - ampere (A)
• Temperature - kelvin (K)
• Luminous intensity - candela (cd)
• Mass - kilogram (kg)

The other derived Quantities
• Area (A): Square Meter (m²)
• Volume (V): Cubic Meter (m³)
• Speed (v): Meter per Second (m/s)

• Acceleration (a): Meter per Second Squared (m/s²)
• Force (F): Newton (N) [kg·m/s²]
• Energy (E): Joule (J) [kg·m²/s²]
• Power (P): Watt (W) [kg·m²/s³]
• Pressure (P): Pascal (Pa) [N/m²]
Dimensions of Physical Quantities (MLT)-Fundamental & Derived

The dimensions of any physical quantity determine its nature. We have seven primary dimensions. Primary
(sometimes it’s called basic) dimensions are defined as independent or fundamental dimensions, from which
other dimensions can be obtained. The primary dimensions are: mass, length, time, temperature, electric current,
amount of light, and amount of matter.

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