مادة الفيزياء الحيوية - الأبعاد والوحدات

Biophysics Course - Dimension & Units

• This is a biophysics lab for PTBA 1105, first level, fall semester 2024-2025.
• Physical quantities can be classified as basic or derived, and further categorized as scalar or vector.
• Basic quantities cannot be expressed in terms of other quantities.
• Examples of basic quantities: Length, Mass, Time, Current, Luminous intensity, Amount of substance, and Temperature (abbreviated as L, M, T, I, J, N, θ).

Basic Definitions

• A basic quantity is a physical quantity that cannot be defined or expressed in terms of other quantities.
• Length, Mass, and Time are the three basic quantities.
• There are four additional basic quantities: Current, Luminous intensity, Amount of substance, and Temperature.

Derived Quantities

• A derived quantity is a physical quantity that can be defined or expressed in terms of two or more basic quantities.
• Examples of derived quantities: Velocity, acceleration, force, and pressure.

Scalar Quantities

• Scalar quantities are defined only by their magnitude (size).
• Examples include price, age, speed, distance, and the area and volume for a shape.

Vector Quantities

• Vector quantities are defined not only by their magnitude (size) but also by their direction.
• Examples include force, velocity, displacement, and the acceleration of shapes.

Dimension vs. Unit

• Dimension describes the physical nature of a quantity (like length, mass, time).
• Unit is the standard used to measure a dimension, giving it a numerical value.
• Examples: Length dimension is [L], and a length unit can be measured in meters (m) or kilometers (km).

SI Base Quantities and Units

• Length: Meter (m)
• Mass: Kilogram (kg)
• Time: Second (s)
• Electric Current: Ampere (A)
• Temperature: Kelvin (K)
• Amount of substance: Mole (mol)
• Luminous intensity: Candela (cd)

Basic Quantities and their Dimensions

• A table listing the names, SI units, and dimensions of the seven basic quantities (length, time, mass, electric current, temperature, amount of substance, and luminous intensity)

System of Units

• Different systems of units exist (e.g., FPS, CGS, MKS).
• Each system defines length, mass, and time units differently.

Area and Volume

• Area is calculated by multiplying length by width.
• Volume is calculated by multiplying length, width, and height.

Dimension and Units of Basic and Derived Quantities

• A table displaying the formulas, dimensions, MKS units, and CGS units for various quantities (mass, length, time, area, volume, velocity, acceleration, force, pressure, and others).

Dimensional Analysis

• A method for checking the validity of physical equations by comparing the dimensions of the left and right sides of the equation.

Conversions Between Units

• Methods for converting between different systems of units(Example: converting Newton to Dyne).

Ratio, Rate, and Gradient

• Ratio compares a quantity to itself.
• Rate is the change of a quantity with respect to time.
• Gradient is the change of a quantity with respect to distance.

Refractive Index

• Refractive index is the ratio of the speed of light in a vacuum to the speed of light in a medium.
• It has no dimensions and no units.