Coulomb's Law — Formula, Units and Worked Examples
Coulomb's law describes the force between electric charges. Learn the formula, the constant k, and a step-by-step numerical example for 2026.
Science in practice: density, concentrations, Ohm’s law and other formulas with worked examples.
Coulomb's law describes the force between electric charges. Learn the formula, the constant k, and a step-by-step numerical example for 2026.
What is entropy and how do you calculate it? We explain the second law of thermodynamics, Boltzmann's formula, and entropy using simple physical examples for 2026.
Step-by-step guide to calculating molar mass for elements and chemical compounds. Includes the periodic table, worked examples and common mistakes.
Understand Ohm's Law with clear examples, the V=IR formula and real-world applications in electronics and electrical engineering. Ideal for students.
Learn how to calculate solution concentration: molarity, mass percentage, molality and more. Clear formulas and worked examples for chemistry students.
Ohm's law in practice: the formula U = I × R, how to find voltage, current and resistance. Worked numerical example in SI units plus power formulas.
How to calculate the density of a substance: the formula ρ = m / V, SI units, converting kg/m³ to g/cm³, and a step-by-step numerical example.
How to calculate the molar concentration of a solution: the formula c = n / V, finding moles from mass, the unit mol/dm³, and a worked example with salt.
How to calculate the pH of a solution from the hydrogen ion concentration: the formula pH = -log[H⁺], the pH scale, acids and bases, and a worked example.
The kinetic energy of a body: the formula Ek = ½mv², the unit joule, the effect of mass and speed, and a step-by-step numerical example in SI units.
Newton's second law of motion: the formula F = m × a, the unit newton, how to calculate force, mass and acceleration, and a worked example in SI units.
How to calculate pressure: the formula p = F / S, the unit pascal, the effect of force and area on pressure, and a step-by-step numerical example in SI.
How to calculate average speed: the formula v = s / t, the units m/s and km/h, unit conversion, and a numerical example with distance and time.
Formulas for the area and perimeter of a square, rectangle, triangle and circle. Units, the difference between area and perimeter, and step-by-step examples.
How to calculate a percentage and a per mille of a number: the formulas, the difference between percent and per mille, converting fractions, and worked examples.
What is the Doppler effect, how does the frequency-shift formula work and where is it used? From ambulance sirens to astronomical red-shift and medical ultrasound.
The Doppler effect is a change in wave frequency observed by a moving receiver or source. Learn the formula, real-life examples, and how to calculate it.
What is radioactive decay, how does the law of half-life work, and how do you calculate the remaining amount of a substance after a given time? Formulas, examples, and applications.
The Archimedes buoyant force determines whether an object sinks or floats. Learn the formula F = ρ x g x V, Archimedes' principle, and its applications in engineering and medicine.
The area of a triangle can be calculated in several ways. Learn the base times height formula, Heron's formula, and the side-and-angle method, with step-by-step examples.
The volume of a cylinder is calculated as pi times radius squared times height. Learn the formulas for volume and surface area, and how to convert the result to liters.
Master the ideal gas law PV=nRT with a step-by-step calculator guide. Includes formula derivations, unit conversions, real gas corrections, and solved chemistry problems.
Logarithms step by step: definition, formulas, properties and worked examples. Learn how to calculate log, ln and log2 without mistakes.
Learn the trigonometric functions sin, cos, tan and cot — definitions, formulas, values for common angles, and applications in geometry and physics.
A complete set of formulas for surface area and volume of solids: cube, cylinder, cone, sphere, prism and more — with worked examples.
How do you convert volume between liters, gallons, m³, milliliters and ounces? Formulas, conversion tables and an online calculator for every unit.
The ideal gas law PV=nRT step by step: what the variables mean, how to calculate pressure, volume and temperature, and examples of applications in physics.
How to convert between Celsius, Fahrenheit and Kelvin temperature scales: formulas, comparison tables and practical everyday examples.
How to convert kilowatt-hours, megajoules, and kilocalories? Conversion formulas and practical examples from energy bills and nutrition labels.