Dynamics

Force, Mass, and Newton's Laws

Dynamics studies the causes of motion, focusing on how forces affect the movement of objects. It is foundational for understanding natural phenomena and analyzing physical systems.

• Force: A vector quantity representing a push or pull acting on an object, measured in newtons (N).

• Mass: A scalar quantity indicating the amount of matter in an object, reflecting its inertia.

• Newton's First Law (Law of Inertia): An object remains at rest or in uniform motion unless acted upon by a net external force.

• Newton's Second Law: The acceleration of an object is proportional to the net force and inversely proportional to its mass:

• Newton's Third Law: For every action, there is an equal and opposite reaction.

Free-Body Diagrams

• Visual tools to analyze forces acting on a single object, depicting all forces as arrows (e.g., gravity, normal, friction, tension).

Contact Forces: Normal and Friction

• Normal Force: Exerted by a surface perpendicular to an object resting on it, balancing the object's weight on a horizontal surface.

• Friction Force: Opposes relative motion between surfaces. Can be static (prevents motion) or kinetic (opposes motion). Magnitude depends on surface nature and normal force.

Linear Momentum and Impulse

• Linear Momentum:

• Impulse:

Conservation of Momentum

• In a closed system with no external forces, total momentum remains constant:

Electric Currents

Electric Current, Ohm’s Law, and Resistance

Electric current describes the flow of electric charge through a conductor, driven by a potential difference.

• Electric Current: (measured in amperes, A)

• Ohm's Law:

• Resistance: , where is resistivity, is length, is cross-sectional area.

Electric Power, EMF, and Terminal Voltage

• Electric Power: , also or

• EMF (Electromotive Force): Energy per unit charge provided by a source (measured in volts).

• Terminal Voltage:

Electric Field and Capacitance

Electric Charge, Static Electricity, and Induced Charge

• Charge is a fundamental property (positive or negative), measured in coulombs (C).

• Static electricity: Accumulation of charge on surfaces.

• Induced charge: Redistribution of charges in a conductor due to an external field.

Electric Field and Field Lines

• Electric Field: (N/C or V/m)

• Field lines originate from positive and terminate at negative charges; density indicates field strength.

Electric Potential, Voltage, and Equipotential Lines

• Electric Potential: Work per unit charge to move a charge from infinity to a point (measured in volts).

• Voltage: Potential difference between two points.

• Equipotential lines are perpendicular to field lines; no work is needed to move a charge along them.

Coulomb’s Law

• , N·m2/C2

Conductors, Dielectrics, and Charge Distribution

• Conductors: Charges move freely, redistribute to cancel internal field.

• Dielectrics: Insulators; become polarized in an electric field, reducing effective field strength.

• Charge accumulates at sharp edges on conductors.

Capacitance and Energy Storage

• Capacitance: (farads, F)

• Energy stored:

Fluids and Solids

Mass, Weight, Density, and Specific Gravity

• Mass: Amount of matter (kg), constant everywhere.

• Weight:

• Density:

• Specific Gravity: Ratio of substance's density to water's density (dimensionless).

Pressure, Pascal’s Principle, and Hydraulic Lift

• Pressure: (Pa = N/m2)

• Pascal’s Principle: Pressure change in a confined fluid is transmitted equally in all directions.

• Hydraulic Lift:

Archimedes’ Principle and Buoyancy

• Buoyant force equals the weight of displaced fluid:

Elasticity, Stress, Strain, Hooke’s Law, and Young’s Modulus

• Stress:

• Strain:

• Hooke’s Law: , where is Young’s modulus.

Geometrical Optics and Wave Nature of Light

Ray Model, Reflection, and Mirrors

• Light modeled as rays for analyzing reflection and refraction.

• Law of Reflection:

• Plane mirrors form virtual, upright images; spherical mirrors (concave/convex) form real or virtual images depending on object position.

Total Internal Reflection and Fiber Optics

• Occurs when light in a denser medium hits the boundary at an angle greater than the critical angle:

• Fiber optics use this principle for light transmission in medical devices.

Refraction, Snell’s Law, and Lenses

• Snell’s Law:

• Index of Refraction:

• Thin Lenses: Focal point, focal length, and optical power ( in diopters).

• Ray tracing for converging (convex) and diverging (concave) lenses; applications include magnifying glasses, the eye, and corrective lenses.

Wave Nature: Huygens' Principle, Diffraction, Interference, and Polarization

• Huygens' Principle: Every point on a wavefront acts as a source of secondary wavelets.

• Diffraction: Bending of light around obstacles/apertures.

• Interference: Overlapping waves produce constructive/destructive patterns (e.g., Young’s double-slit experiment).

• Polarization: Restricts light oscillations to a single plane; used in sunglasses and medical imaging.

Kinematics

Vectors, Scalars, and Vector Operations

• Scalars: Magnitude only (e.g., distance, speed).

• Vectors: Magnitude and direction (e.g., displacement, velocity, acceleration).

• Components: ,

• Vector addition (analytical): , ,

Frames of Reference and Displacement

• Frame of reference: Perspective from which motion is observed.

• Displacement: Vector from initial to final position.

Velocity and Acceleration

• Velocity:

• Acceleration:

Constant Acceleration and Projectile Motion

• Kinematic equations:

• Projectile motion: Horizontal and vertical components analyzed separately.

  • Time of flight:

  • Maximum height:

  • Range:

Magnetism, Electromagnetic Induction, and Electromagnetic Waves

Magnets and Magnetic Fields

• Magnetic fields originate from north and terminate at south poles; measured in teslas (T).

Magnetic Field of Currents

• Current-carrying wires produce magnetic fields (right-hand rule).

• Solenoids create uniform fields; adding a ferromagnetic core increases field strength.

Force on Currents and Charges

• Lorentz force:

• Force on wire:

Faraday’s Law and Lenz’s Law

• Faraday’s law: ,

• Lenz’s law: Induced current opposes the change in magnetic flux.

Generators, Transformers, and Power Transmission

• Transformers:

• High-voltage transmission reduces energy loss.

Electromagnetic Waves and Spectrum

• Electromagnetic waves: Oscillating electric and magnetic fields, speed m/s.

• Spectrum includes radio, microwave, IR, visible, UV, X-rays, gamma rays.

• Produced by accelerating charges.

Nuclear Physics and Radioactivity

Nucleus Structure, Binding Energy, and Nuclear Forces

• Nucleus: Protons and neutrons (nucleons); size , fm.

• Strong nuclear force binds nucleons; acts over short distances.

Radioactivity: Alpha, Beta, Gamma Decay

• Alpha decay: Emission of (helium nucleus).

• Beta decay: Emission of electron/positron; neutron-proton conversion.

• Gamma decay: Emission of high-energy photons; no change in nucleon number.

Law of Radioactive Decay and Half-Life

• Half-life:

Nuclear Reactions, Fission, and Fusion

• Transmutation: Change of one element to another via nuclear reactions.

• Fission: Heavy nucleus splits, releasing energy and neutrons.

• Fusion: Light nuclei combine, releasing energy ().

Nuclear Reactors and Medical Applications

• Reactors use controlled fission for energy and isotope production.

• Applications: Imaging (PET, gamma cameras), radiotherapy, sterilization, diagnostics.

Sounds

Characteristics of Sound

• Sound: Longitudinal mechanical wave; frequency (Hz), wavelength (), speed (), amplitude, period ().

Sound Intensity and Level

• Intensity: (W/m2)

• Intensity level: , W/m2

Ear and Loudness

• Outer, middle, and inner ear convert sound waves to electrical signals.

• Loudness is subjective, depends on intensity and frequency.

Doppler Effect

• Used in medical Doppler ultrasound for blood flow measurement.

Sources of Sound and Standing Waves

• Vibrating strings:

• Open pipes: ; closed pipes:

• Standing waves: Nodes (no displacement), antinodes (max displacement).

Temperature and Kinetic Theory of Gases

Temperature and Molecular Kinetic Energy

• Temperature: Average kinetic energy of particles.

• Kelvin scale: Absolute temperature, starts at 0 K.

Thermal Equilibrium and Zeroth Law

• If two systems are each in thermal equilibrium with a third, they are in equilibrium with each other.

Ideal Gas Law

Heat, Internal Energy, and First Law of Thermodynamics

• Heat: Energy transfer due to temperature difference.

• Internal energy (ideal gas):

• First law:

Specific Heat and Latent Heat

• Specific heat:

• Latent heat:

Heat Engines and Second Law of Thermodynamics

• Efficiency:

• Second law: Entropy increases; heat flows from hot to cold spontaneously.

Vibration and Waves

Simple Harmonic Motion (SHM)

• Restoring force:

• Displacement: ,

Energy in SHM

• Kinetic:

• Potential:

• Total:

Simple Pendulum

• Period:

Resonance and Forced Vibration

• Resonance: Large amplitude when driving frequency matches natural frequency.

Wave Motion

• Transverse: Oscillations perpendicular to propagation (e.g., light).

• Longitudinal: Oscillations parallel to propagation (e.g., sound).

• Wave speed:

Wave Propagation: Reflection, Refraction, Diffraction

• Reflection: Angle of incidence equals angle of reflection.

• Refraction: Bending due to speed change in different media.

• Diffraction: Spreading around obstacles/openings.

Work, Power, and Energy

Work, Kinetic and Potential Energy

• Work:

• Kinetic energy:

• Potential energy (gravitational):

• Elastic potential energy:

Power

• or

Conservative and Non-Conservative Forces

• Conservative: Path-independent (e.g., gravity, elastic); energy stored as potential energy.

• Non-conservative: Path-dependent (e.g., friction); energy dissipated as heat or sound.

Mechanical Energy Conservation and Transformations

• (if only conservative forces act)

• Energy can transform between mechanical, thermal, chemical, and electrical forms.

Work-Energy Principle

Additional info: These notes integrate foundational physics concepts with applications relevant to medicine, such as biomechanics, medical imaging, and diagnostic technologies. Mastery of these topics is essential for medical studies and clinical practice.