Key Concepts in Physics

Key Concepts in Physics

Fundamental Forces

1. Gravitational Force

   • Attraction between masses; governs planetary motion.

2. Electromagnetic Force

   • Interaction between charged particles; responsible for electricity, magnetism, and light.

3. Weak Nuclear Force

   • Responsible for radioactive decay; plays a role in nuclear processes.

4. Strong Nuclear Force

   • Holds protons and neutrons together in atomic nuclei.

Laws of Motion

1. Newton's First Law

   • An object at rest stays at rest, and an object in motion stays in motion unless acted upon by an external force.

2. Newton's Second Law

   • Force equals mass times acceleration (F = ma).

3. Newton's Third Law

   • For every action, there is an equal and opposite reaction.

Energy

1. Kinetic Energy (KE)

   • Energy of motion; KE = (1/2)mv², where m = mass and v = velocity.

2. Potential Energy (PE)

   • Stored energy due to position; gravitational PE = mgh, where h = height.

3. Law of Conservation of Energy

   • Energy cannot be created or destroyed, only transformed from one form to another.

Thermodynamics

1. First Law of Thermodynamics

   • Energy is conserved; ΔU = Q - W, where ΔU = change in internal energy, Q = heat added, W = work done.

2. Second Law of Thermodynamics

   • Entropy of an isolated system always increases; energy tends to disperse.

3. Third Law of Thermodynamics

   • As temperature approaches absolute zero, the entropy of a perfect crystal approaches zero.

Waves and Oscillations

1. Mechanical Waves

   • Require a medium; examples include sound waves.

2. Electromagnetic Waves

   • Do not require a medium; examples include light, radio waves.

3. Wave Properties

   • Wavelength, frequency, amplitude, speed.

4. Harmonic Motion

   • Repetitive back and forth motion; characterized by oscillation and restoring force.

Modern Physics

1. Quantum Mechanics

   • Describes physical phenomena at atomic and subatomic levels; introduces concepts like wave-particle duality.

2. Relativity

   • Einstein’s theory; includes Special Relativity (motion at high speeds) and General Relativity (gravity as curvature of spacetime).

3. Particle Physics

   • Study of fundamental particles; includes quarks, leptons, and bosons.

Applications of Physics

1. Engineering

   • Principles used in mechanics, electronics, fluid dynamics.

2. Astrophysics

   • Study of celestial bodies and the universe's physical properties.

3. Medical Physics

   • Application of physics concepts in medical imaging and treatment.

Measurement Units

1. SI Units

   • Length: meter (m)
   • Mass: kilogram (kg)
   • Time: second (s)
   • Temperature: kelvin (K)

2. Other Units

   • Force: Newton (N)
   • Energy: Joule (J)
   • Power: Watt (W)

Fundamental Forces

• Gravitational Force: Attracts objects with mass; governs planetary motion.
• Electromagnetic Force: Interaction between charged particles; responsible for electricity, magnetism, and light.
• Weak Nuclear Force: Causes radioactive decay, involved in nuclear processes.
• Strong Nuclear Force: Binds protons and neutrons together in atomic nuclei.

Laws of Motion

• Newton's First Law: A stationary object remains at rest, and a moving object continues at constant speed in a straight path unless acted upon by an external force.
• Newton's Second Law: The net force on an object is equal to its mass times its acceleration (F = ma).
• Newton's Third Law: For every action force, there is an equal and opposite reaction force.

Energy

• Kinetic Energy (KE): The energy of motion. KE = (1/2)mv², where m is mass and v is velocity.
• Potential Energy (PE): Stored energy due to an object's position. Gravitational PE = mgh, where h is height.
• Law of Conservation of Energy: Energy cannot be created or destroyed, only transformed from one form to another.

Thermodynamics

• First Law of Thermodynamics: Energy is conserved. ΔU = Q - W, where ΔU is change in internal energy, Q is heat added, and W is work done.
• Second Law of Thermodynamics: Entropy of an isolated system always increases; energy tends to become more dispersed.
• Third Law of Thermodynamics: As temperature approaches absolute zero, the entropy of a perfect crystal approaches zero.

Waves and Oscillations

• Mechanical Waves: Require a medium through which to travel; examples include sound waves.
• Electromagnetic Waves: Do not require a medium to travel; examples include light and radio waves.
• Wave Properties: Wavelength, frequency, amplitude, and wave speed.
• Harmonic Motion: Repetitive back and forth motion characterized by oscillations and a restoring force.

Modern Physics

• Quantum Mechanics: Explains physical phenomena at the atomic and subatomic levels; introduces concepts like wave-particle duality.
• Relativity: Einstein's theories, including Special Relativity (motion at high speeds) and General Relativity (gravity as curvature of spacetime).
• Particle Physics: Studies fundamental particles, including quarks, leptons, and bosons.

Applications of Physics

• Engineering: Applies physics principles in mechanics, electronics, and fluid dynamics.
• Astrophysics: Studies celestial objects and the universe's physical properties.
• Medical Physics: Applies physics concepts in medical imaging and treatment.

Measurement Units

• SI Units:

  • Length: meter (m)
  • Mass: kilogram (kg)
  • Time: second (s)
  • Temperature: kelvin (K)

• Other Units:

  • Force: Newton (N)
  • Energy: Joule (J)
  • Power: Watt (W)