Physics Reference Sheet
Units and Constants
- Fundamental Units:
- Length: meter (m)
- Mass: kilogram (kg)
- Time: second (s)
- Electric current: ampere (A)
- Temperature: kelvin (K)
- Amount of substance: mole (mol)
- Luminous intensity: candela (cd)
| Constant | Symbol | Value |
|---|---|---|
| Speed of light in vacuum | c | 299,792,458 m/s |
| Gravitational constant | G | 6.674 x 10^-11 N m^2/kg^2 |
| Planck’s constant | h | 6.626 x 10^-34 J s |
| Boltzmann constant | k | 1.381 x 10^-23 J/K |
| Elementary charge | e | 1.602 x 10^-19 C |
| Permittivity of free space | ε₀ | 8.854 x 10^-12 F/m |
| Permeability of free space | μ₀ | 4π x 10^-7 T m/A |
Kinematics
- Displacement (s): Δs = sₜ - s₀
- Velocity (v): v = Δs / Δt
- Acceleration (a): a = Δv / Δt
- Equations of motion:
- v = v₀ + at
- s = s₀ + v₀t + (1⁄2)at^2
- v^2 = v₀^2 + 2a(s - s₀)
Dynamics
- Newton’s laws of motion:
- An object at rest stays at rest, and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
- The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass (F = ma).
- For every action, there is an equal and opposite reaction.
- Work (W): W = Fd cos(θ)
- Power (P): P = W / t
- Kinetic energy (KE): KE = (1⁄2)mv^2
- Potential energy (PE): PE = mgh
Thermodynamics
- Ideal gas law: PV = nRT
- First law of thermodynamics: ΔU = Q - W
- Second law of thermodynamics: The total entropy of an isolated system always increases over time.
Electricity and Magnetism
- Coulomb’s law: F = k(q₁q₂)/r^2
- Ohm’s law: V = IR
- Faraday’s law of induction: ε = -dΦ/dt
- Lenz’s law: The direction of the induced current is such that it opposes the change in magnetic flux that produced it.
Waves and Optics
- Wave equation: v = fλ
- Snell’s law: n₁ sin(θ₁) = n₂ sin(θ₂)
- Young’s double-slit experiment: Δy = (mλL)/d
Modern Physics
- Photoelectric effect: KE_max = hf - φ
- De Broglie wavelength: λ = h/p
- Heisenberg uncertainty principle: Δx Δp ≥ h/4π
Frequently Used Formulas
- Centripetal force: F_c = mv^2/r
- Torque: τ = rF sin(θ)
- Angular momentum: L = Iω
- Bernoulli's equation: P + (1/2)ρv^2 + ρgh = constant
Key Concepts
Conservation Laws
- Conservation of energy
- Conservation of momentum
- Conservation of angular momentum
Wave-Particle Duality
Matter exhibits both wave-like and particle-like properties, depending on the observation context.
FAQ Section
What is the difference between speed and velocity?
+Speed is a scalar quantity that describes how fast an object is moving, while velocity is a vector quantity that describes both the speed and direction of an object's motion.
How does the photoelectric effect support the particle nature of light?
+The photoelectric effect demonstrates that light energy is quantized into discrete packets (photons), which behave like particles. The kinetic energy of emitted electrons depends on the frequency of incident light, not its intensity, supporting the particle model of light.
What is the significance of the Heisenberg uncertainty principle?
+The Heisenberg uncertainty principle states that it is impossible to simultaneously know the exact position and momentum of a particle. This principle is a fundamental aspect of quantum mechanics and has significant implications for our understanding of the behavior of particles at the atomic and subatomic levels.
How does the ideal gas law relate to kinetic theory?
+The ideal gas law (PV = nRT) is derived from the kinetic theory of gases, which assumes that gas particles are in constant, random motion and undergo elastic collisions. The law relates the macroscopic properties of a gas (pressure, volume, temperature) to the microscopic properties of its particles (number of moles, gas constant).
What is the difference between conductor and insulator materials?
+Conductor materials, such as metals, have free electrons that can move easily in response to an electric field, allowing electric current to flow. Insulator materials, such as rubber or glass, have tightly bound electrons that cannot move freely, preventing the flow of electric current.
How does special relativity modify our understanding of space and time?
+Special relativity, proposed by Albert Einstein, introduces the concept of spacetime, where space and time are intertwined and relative to the observer's frame of reference. It modifies our understanding of space and time by showing that they are not absolute, but rather depend on the relative motion of observers. Key consequences include time dilation, length contraction, and the equivalence of mass and energy (E=mc^2).
Note: This reference sheet provides a concise overview of key physics concepts, formulas, and constants. For a more in-depth understanding, consult reputable physics textbooks or online resources.
"Physics is not just a collection of facts and formulas, but a way of thinking about the world. It encourages us to ask questions, challenge assumptions, and seek a deeper understanding of the fundamental principles that govern our universe." – Anonymous Physicist
Mastering physics requires a strong foundation in mathematics, critical thinking skills, and the ability to apply theoretical concepts to real-world problems. By understanding the fundamental principles and equations outlined in this reference sheet, you’ll be well on your way to developing a deeper appreciation for the beauty and complexity of the physical world.
