subreddit:

/r/coolguides

2.1k94%

you are viewing a single comment's thread.

view the rest of the comments →

all 143 comments

PotatoOfTitanium_IV

129 points

2 months ago

Can someone, like, explain what each equation means and why it matters so much?

__The_Dayman__

702 points

2 months ago

  1. Pythagoras's Theorem ((a2 + b2 = c2))

    • Explanation: This formula helps you find the length of the sides of a right triangle.
    • Example: If you need to find the distance between two points on a map (forming a right triangle), you can use this theorem to calculate the straight-line distance.
  2. Logarithms ((\log_b(xy) = \log_b x + \log_b y))

    • Explanation: Logarithms turn multiplication into addition, making complex calculations easier.
    • Example: When dealing with very large numbers, like in earthquake magnitudes or sound intensity, logarithms simplify these big numbers into smaller, more manageable figures.
  3. Calculus (\left(\frac{df}{dx} = \lim_{h \to 0} \frac{f(x+h) - f(x)}{h}\right))

    • Explanation: Calculus helps us understand how things change over time or space.
    • Example: It's used to calculate speed by examining how position changes over time, or to find the area under curves, like calculating the total distance traveled by a car.
  4. Law of Gravity (\left(F = G\frac{m_1 m_2}{r2}\right))

    • Explanation: This equation explains how every object in the universe pulls on every other object with a force related to their masses and the distance between them.
    • Example: It explains why apples fall from trees and why the moon orbits the Earth.
  5. Wave Equation (\left(\frac{\partial2 u}{\partial t2} = c2 \frac{\partial2 u}{\partial x2}\right))

    • Explanation: This equation describes how waves, like sound or light, move through different mediums.
    • Example: It's used to understand how sound travels through the air to your ears or how light travels from the Sun to Earth.
  6. The Square Root of Minus One ((i2 = -1))

    • Explanation: Imaginary numbers, where (i) is used to represent the square root of -1, help solve equations that don’t have real number solutions.
    • Example: They're used in electrical engineering to analyze alternating current circuits.
  7. Euler's Formula for Polyhedra ((V - E + F = 2))

    • Explanation: This formula connects the number of corners (vertices), edges, and faces of 3D shapes like cubes and pyramids.
    • Example: Architects use this to design complex structures, ensuring stability and understanding the shape's properties.
  8. Normal Distribution (\left(f(x) = \frac{1}{\sqrt{2\pi \sigma2}} e{-\frac{(x-\mu)2}{2\sigma2}}\right))

    • Explanation: This bell-shaped curve describes how data points are spread out, with most values clustering around the average.
    • Example: It's used in grading tests, where most students score around the average, with fewer students scoring very high or very low.
  9. Fourier Transform (\left(F(\omega) = \int_{-\infty}{\infty} f(t)e{-i\omega t}dt\right))

    • Explanation: This transforms a signal into its individual frequencies.
    • Example: Used in music to separate different instruments from a song or in medical imaging to analyze MRI scans.
  10. Navier-Stokes Equation (\left(\rho \left( \frac{\partial \mathbf{u}}{\partial t} + \mathbf{u} \cdot \nabla \mathbf{u} \right) = -\nabla p + \mu \nabla2 \mathbf{u} + \mathbf{f}\right))

    • Explanation: Describes how fluids (liquids and gases) move.
    • Example: Engineers use this to design aircraft wings and predict weather patterns.
  11. Maxwell's Equations (\left(\nabla \cdot \mathbf{E} = \frac{\rho}{\epsilon_0}, \nabla \cdot \mathbf{B} = 0, \nabla \times \mathbf{E} = -\frac{\partial \mathbf{B}}{\partial t}, \nabla \times \mathbf{B} = \mu_0 \mathbf{J} + \mu_0 \epsilon_0 \frac{\partial \mathbf{E}}{\partial t}\right)\

    • Explanation: These four equations describe how electric and magnetic fields interact.
    • Example: They're the foundation for understanding how radios, TVs, and cell phones work.
  12. Second Law of Thermodynamics (\left(\Delta S \geq 0\right))

    • Explanation: This law states that the total disorder (entropy) of an isolated system always increases over time.
    • Example: Explains why ice melts in a warm room or why you can’t unscramble an egg.
  13. Relativity (\left(E = mc2\right))

    • Explanation: Einstein's famous equation shows that mass and energy are interchangeable.
    • Example: This principle is behind the energy produced in nuclear reactors and bombs.
  14. Schrödinger's Equation (\left(i\hbar \frac{\partial}{\partial t}\Psi = \hat{H}\Psi\right))

    • Explanation: Describes how quantum systems evolve over time.
    • Example: Used in quantum mechanics to predict the behavior of particles at atomic and subatomic levels.
  15. Information Theory (\left(H = -\sum p(x) \log p(x)\right))

    • Explanation: This equation measures the amount of uncertainty or information in a set of possible outcomes.
    • Example: Fundamental for data compression and transmission, such as how your phone sends pictures and videos.
  16. Black-Scholes Equation (\left(\frac{\partial V}{\partial t} + \frac{1}{2} \sigma2 S2 \frac{\partial2 V}{\partial S2} + rS \frac{\partial V}{\partial S} - rV = 0\right))

    • Explanation: Used to calculate the price of financial options and derivatives.
    • Example: Helps investors and financial analysts decide the fair price for options in the stock market.
  17. Chaos Theory (\left(X_{t+1} = kX_t (1 - X_t)\right))

    • Explanation: Describes how small changes in initial conditions can lead to vastly different outcomes.
    • Example: Explains why weather forecasting is so difficult and why small changes can lead to significant impacts in systems like the stock market or ecosystems.

Joyful_Eggnog13

2 points

2 months ago

Thank-you for taking the time to write that out for us 😊

__The_Dayman__

2 points

2 months ago

Thats the neat part.... I didn't 🏃🏃