# تلخيص الدرس الأول فيزياء صف تاسع متقدم

الصف الصف التاسع المتقدم فيزياء الصف التاسع المتقدم فيزياء تاسع متقدم فصل اول 1.77 MB 54 2020-07-10, 19:39 مساء

PHY40-Lesson1

Units and Dimensions

1. Identiy Basic and Derived physical quantities.

2. Introduce the units of certain physical quantities.

3. Introduce Prefixes and ways of conversion.

4. Identify Dimensional Analysis.

Physics is the study of Nature, Matter, and Energy.

To start with physics we have to know what we call by Physical Quantities

Physical Quantities

Basic

Derived

Table 1 SI Base Units

Base Quantity → Base Unit → Symbol

Length → meter → m

Mass → kilogram → kg

Time → second → s

Temperature → kelvin → K

Amount of a substance → mole → mol

Electric current → ampere → A

Luminous intensity → candela → cd

Examples;

The length of a football field is 120 m.

The physics book has a mass of 1 kg.

The electric current flowing into the house is around 2 A.

Derived quantities are derived from basic quantities through combining them in different ways such as by multiplying and dividing.

Some examples on derived units are

Derived Quantity → Unit

Velocity → [m/s]

Area → [m²] [m x m]

Volume → m3

Density → Kg/m3

Force → Kg x m/s2 or N (Newton)

Acceleration → m/s2

Pressure → N/m2

Energy → J (Joules)

Power → J/s or Watt

The length of a football field is 120 m

The height of khalid is 167 cm

The distance from Abu Dhabi to Al ain is 150 km Unit

Dimensional Analysis

Physics is described by equations such as

Force = mass x acceleration

momentum = mass x velocity

velocity = displacement / time

Both sides of the equation should have the same unit. This is what we call by Dimensional Analysis.

Check whether the following formulas are dimensionally consistent?

d=distance [m]

v= velocity [m/5]

t= time [s]

a= acceleration [m/5a]

F= Force [kgom/5a]