Cobalt-60 and Linear Accelerators in Radiation Therapy
Ionizing Radiation Fundamentals
Capable of photons or other particles separating electrons from atoms upon contact. All physical processes involve mass transfer and/or energy processing.
Criteria for Useful Radioactive Sources (Radiophotons)
- Must provide radiation penetrating deep enough to react with the target area.
- Must provide a sufficient amount of energy where the volume is small (If the source has considerable thickness, it absorbs part of the radiation; if it does not, it does not absorb the
Kinematics of Projectiles: Motion, Trajectory, and Formulas
Kinematics of Projectile Motion
Defining Projectiles
- Projectiles are bodies projected into the air that possess both horizontal and vertical components of motion.
- Examples include: shot put, discus, javelin, and the human body during a jump.
- Gravity determines the maximum height achieved by the projectile.
- The horizontal component determines the maximum distance (range) the projectile reaches.
- In real-world scenarios, only air and wind resistance significantly affect the projectile’s motion.
Note on Air
Read MoreEssential Physics Practicals: Methods and Analysis
1. Mass and Weight Relationship Investigation
Step-by-Step Procedure
- Attach the spring balance or Newton meter securely so it hangs vertically.
- Place the first known mass (e.g., 100 g) on the balance hook.
- Wait for the reading to stabilize and record the weight (in Newtons, N).
- Repeat steps 2–3 for several masses (e.g., 200 g, 300 g, 400 g).
- Plot a graph of weight (N) against mass (kg).
Experimental Variables
- Independent: Mass (kg)
- Dependent: Weight (N)
- Control: Location (keep experiment on Earth, constant
Essential Biomechanics Formulas and Human Motion Principles
Core Biomechanics Formulas for Human Motion Analysis
1. Kinematics (Motion Without Forces)
Kinematics describes motion without considering the forces that cause it.
Key Linear Formulas:
- Displacement (Δx):
Δx = x₂ − x₁
Example: If a sprinter moves from 2 m to 8 m → Δx = 6 m
- Velocity (v):
v = Δx / Δt
Example: 6 m in 2 s → v = 6 / 2 = 3 m/s
- Acceleration (a):
a = Δv / Δt
Example: Speed changes from 2 m/s to 6 m/s in 2 s → a = (6−2)/2 = 2 m/s²
Angular Motion Formulas:
- Angular Displacement (θ)
Physics Fundamentals: Work, Heat Transfer, and Electrical Circuit Calculations
Work, Power, and Energy Calculations
Work Done Lifting a Load
Question: How much work is done in lifting a 500 kg load to a height of 40 m?
Answer: 1.96 × 108 J
Motor Power Calculation
Question: How powerful is a motor that can lift a 1200 kg load 10 m in 20 s?
Answer: 5886 Watts
Work and Lifting Height
Question: Which of the following statements is true regarding the work associated with lifting a box to a certain height?
Answer: All of these will require the same amount of work.
Law of Conservation of
Historical Development of Planetary Motion Theories
1. Ptolemy’s Geocentric Model (2nd Century)
- Model geocentric: the Earth is at the center of the universe.
- All the planets and fixed stars move in circular orbits around the Earth.
- To explain the motion of the planets against the background of fixed stars (retrograde motion), it was necessary to introduce epicycles and deferents.
- Although mathematically complicated, the model fit well with observations and could be applied practically (navigation, predicting eclipses, etc.).