Key Concepts in Physics

Key Concepts in Physics

1. Mechanics

• Kinematics: Study of motion without considering forces.

  • Displacement, velocity, acceleration.
  • Equations of motion (uniform acceleration).

• Dynamics: Study of forces and their effects on motion.

  • Newton's Laws of Motion:
    1. An object at rest stays at rest; an object in motion stays in motion unless acted upon.
    2. F = ma (Force equals mass times acceleration).
    3. For every action, there is an equal and opposite reaction.

• Work, Energy, and Power:

  • Work = Force × Displacement × cos(θ).
  • Kinetic Energy (KE) = 1/2 mv².
  • Potential Energy (PE) = mgh (for gravitational).
  • Power = Work/time.

2. Thermodynamics

• Laws of Thermodynamics:

  1. Energy cannot be created or destroyed, only transformed.
  2. Entropy of an isolated system always increases.
  3. Absolute zero is unattainable.

• Heat Transfer:

  • Conduction, convection, radiation.
  • Specific heat and calorimetry.

3. Waves and Oscillations

• Wave Properties:

  • Wavelength, frequency, amplitude, speed.
  • Types: Transverse and longitudinal waves.

• Sound Waves: Longitudinal waves; speed depends on medium.

• Oscillations: Simple harmonic motion, damped, and forced oscillations.

4. Electricity and Magnetism

• Electricity:

  • Current (I), voltage (V), resistance (R) - Ohm’s Law: V = IR.
  • Circuits: Series and parallel configurations.

• Magnetism:

  • Magnetic fields, forces on moving charges.
  • Electromagnetic induction (Faraday's Law).

5. Modern Physics

• Quantum Mechanics:

  • Wave-particle duality.
  • Heisenberg Uncertainty Principle.
  • Quantum states and superposition.

• Relativity:

  • Special Relativity: Time dilation, length contraction, E=mc².
  • General Relativity: Gravity as curvature of spacetime.

6. Fundamental Forces

• Four Fundamental Forces:
  • Gravitational: Attraction between masses.
  • Electromagnetic: Interaction between charged particles.
  • Weak Nuclear: Responsible for radioactive decay.
  • Strong Nuclear: Holds atomic nuclei together.

7. Astrophysics

• Structure of the Universe:
  • Galaxies, stars, black holes, and cosmology.
  • Big Bang Theory and expansion of the universe.

Applications of Physics

• Engineering, medicine (radiology, MRI), technology (semiconductors), environmental science.

Key Formulas

• Kinematics:
  • v = u + at
  • s = ut + 1/2 at²
• Energy:
  • KE = 1/2 mv²
  • PE = mgh
• Electric Power:
  • P = IV

Mechanics

• Kinematics: Concerned with describing motion using displacement, velocity, and acceleration; applies uniform acceleration equations.
• Dynamics: Explores how forces interact with motion; described by Newton's Laws:
  • First Law: Objects remain in their state of motion unless acted upon.
  • Second Law: Force (F) is the product of mass (m) and acceleration (a), represented by F = ma.
  • Third Law: Every action has an equal and opposite reaction.
• Work, Energy, and Power:
  • Work calculated as the product of force and displacement in the direction of force.
  • Kinetic Energy (KE) formula: KE = 1/2 mv², while Potential Energy (PE) for gravitational fields is PE = mgh.
  • Power is defined as the rate of doing work: Power = Work/time.

Thermodynamics

• Laws of Thermodynamics:
  • First Law: Energy conservation; energy can only change forms.
  • Second Law: Entropy in an isolated system tends to increase.
  • Third Law: Absolute zero is a theoretical limit not achievable.
• Heat Transfer: Involves conduction, convection, and radiation. Specific heat capacity used in calorimetry to measure heat transfer.

Waves and Oscillations

• Wave Properties: Characterized by wavelength, frequency, amplitude, and speed; categorized as transverse or longitudinal.
• Sound Waves: A type of longitudinal wave whose speed varies based on the medium through which it travels.
• Oscillations: Includes types like simple harmonic motion, damped, and forced oscillations, important for understanding periodic motion.

Electricity and Magnetism

• Electricity:
  • Key terms: Current (I), Voltage (V), Resistance (R) governed by Ohm’s Law: V = IR.
  • Circuits can be configured in series or parallel, affecting total resistance and current flow.
• Magnetism: Involves magnetic fields and the forces experienced by moving charges; principles of electromagnetic induction are governed by Faraday's Law.

Modern Physics

• Quantum Mechanics: Highlights wave-particle duality, Heisenberg's Uncertainty Principle, and concepts of quantum states and superposition.
• Relativity:
  • Special Relativity introduces phenomena such as time dilation and length contraction, encapsulated in the equation E=mc².
  • General Relativity conceptualizes gravity as the deformation of spacetime.

Fundamental Forces

• Four Fundamental Forces govern interactions:
  • Gravitational: Attraction between masses.
  • Electromagnetic: Forces between charged particles.
  • Weak Nuclear: Causes processes like radioactive decay.
  • Strong Nuclear: Binds protons and neutrons within atomic nuclei.

Astrophysics

• Structure of the Universe: Explores galaxies, stars, and black holes; foundational theories like the Big Bang explain the universe's expansion.

Applications of Physics

• Physics principles are essential in diverse fields such as engineering, medicine (e.g., radiology, MRI), technology (e.g., semiconductors), and environmental science.

Key Formulas

• Kinematics:
  • Velocity: v = u + at
  • Displacement: s = ut + 1/2 at²
• Energy:
  • Kinetic Energy: KE = 1/2 mv²
  • Potential Energy: PE = mgh
• Electric Power:
  • Power formula: P = IV