Fundamental Physics for Radiographers Quiz

Course Title and Instructor

• Course: RXD12402 Fundamental Physics for Radiographers
• Instructor: Izza Nadia binti Mohd Maulana, Senior Lecturer

Subtopics

• Introduction to physics
• Work, Energy and Power
• Properties of Electrical Charges
• Law of Conservation of Energy
• Heat and Temperature
• Heat Transfer
• Heat Energy in X-ray Tube

Learning Outcomes

• Describe work, energy (potential and kinetic), and power
• Describe the law of conservation of energy
• Describe electrical charges and Coulomb's Law
• Describe heat and temperature
• Describe the processes of heat transfer (conduction, convection, and radiation)

Introduction to Physics

• Physics deals with the interactions of energy, matter, space, and time
• Aims to describe how everything functions, from tiny particles to large objects

Physical Quantities and Units

• Physical quantities are defined by measurement or calculation
• Measurements use standardized units for meaningful comparison

Base Quantities

• Length (metre, m)
• Mass (kilogram, kg)
• Time (second, s)
• Temperature (Kelvin, K)
• Current (Ampere, A)
• These are fundamental, not derived from other quantities

Derived Quantities

• Area (m²) = length x length
• Volume (m³) = length x length x length
• Density (kg/m³) = mass / volume
• Speed (m/s) = length / time
• Acceleration (m/s²) = change in velocity / time
• Force (kg m/s² or N) = mass x acceleration
• Work (Nm or J) = force x distance
• Power (J/s or W) = work / time

Metric Prefixes

• Metric conversions use powers of 10
• Simplifies large and small values comparisons

Displacement vs. Distance

• Displacement = change in position (magnitude and direction)
• Distance = total path length between two points

Work

• Work (W) = force (F) x distance (d) x cos θ
• Unit: Joule (J) = Nm
• θ is the angle between force and displacement

Example - Work

• A 100 N force at 30° applied to move a 15 kg object 5m horizontally: W = 433J

Energy in Kinematics

• Two types: potential and kinetic energy

Potential Energy (PE)

• Energy due to position
• Formula: PE = mgh (mass x gravity x height )
• Unit: Joule (J)
• g = 9.8 m/s² or 10 m/s² (acceleration due to gravity)

Example 1 - PE

• Rock of mass 0.86 kg at 10.3 m high: PE = 86.81J

Example 2 - PE

• 9.56 kg mass raised 4.25 m: PE = 398.17 J

Kinetic Energy (KE)

• Energy due to motion
• Formula: KE = 1/2 mv² (1/2 x mass x velocity²)
• Unit: Joule (J)

Example 1 - KE

• Elephant with 2500 kg mass at 6.2 m/s speed: KE = 48,050 J

Example 2 - KE

• 3.8 kg shot-put thrown at 20 m/s speed: KE = 760 J

Conservation of Energy

• Energy cannot be created or destroyed, just transformed
• KE + PE = constant (in a closed system without friction)

The Work-Energy Theorem

• KEi + PEi + Wnc = KEf + PEf
• KEi = initial kinetic energy
• PEi = initial potential energy
• KEf = final kinetic energy
• PEf = final potential energy
• Wnc = non-conservative work done (friction, etc)

Heat Transfer Types

• Conduction (transfer by direct contact)
• Convection (transfer by mass motion of fluids)
• Radiation (transfer by electromagnetic waves)

Example - Conduction

• Ironing clothes involves heat transfer from the hot iron to the clothes

Heat vs. Temperature

• Heat = energy in transit
• Temperature = degree of hotness/coldness

Specific Heat Capacity

• Quantity of heat required to raise the temperature of 1kg of substance by 1°C/K
• Formula: c = Q/mΔT
• Units: J/kg·K

Heat Transfer in X-Ray Tube

• 99% of electron kinetic energy is converted to heat

• X-ray tube cooling methods (radiation, conduction, convection, and oil)
• Heat Unit (HU) = kVp x mA x time (important for X-ray exposure calculations)