A comprehensive guide to essential physics and chemistry formulas. Whether you're a student, science professional, or simply curious, use CalKit's science calculators to compute results instantly.
1. Mechanics: Force & Motion
Mechanics is the foundation of physics, dealing with motion and the forces that cause it.
Newton's Second Law: F = ma
Formula
F = m × a
Force (N) = Mass (kg) × Acceleration (m/s²)
A 1,500 kg car accelerating at 2 m/s² requires F = 1,500 × 2 = 3,000 N of force.
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Force Calculator
Calculate force from mass and acceleration
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Speed, Distance & Time
Formula
v = d / t
Speed (m/s) = Distance (m) / Time (s)
Driving 400 km at 100 km/h takes 400 / 100 = 4 hours.
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Speed-Distance-Time Calculator
Easily compute speed, distance, or time
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2. Electricity: Ohm's Law
Formula
V = I × R
Voltage (V) = Current (A) × Resistance (Ω)
Ohm's Law relates voltage, current, and resistance. It can be rearranged to find any of the three values: V = IR, I = V/R, or R = V/I.
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LED resistor selection
For a 5V supply with a 2V LED at 20mA: R = (5-2) / 0.02 = 150Ω.
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Ohm's Law Calculator
Calculate voltage, current, or resistance
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3. Matter: Density & Ideal Gas Law
Density
Formula
ρ = m / V
Density (kg/m³) = Mass (kg) / Volume (m³)
Density tells us how much mass is packed into a given volume. Ice floats on water because its density (~917 kg/m³) is lower than water's (1,000 kg/m³).
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Density Calculator
Calculate density from mass and volume
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Ideal Gas Law
Formula
PV = nRT
Pressure × Volume = Moles × Gas constant (8.314 J/mol·K) × Temperature (K)
The ideal gas law connects pressure, volume, temperature, and moles. A balloon expands on a hot day because increasing temperature (T) increases volume (V) at constant pressure.
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Ideal Gas Law Calculator
Compute gas state variables using PV=nRT
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4. Energy: Kinetic & Potential Energy
Formulas
KE = ½mv² | PE = mgh
Kinetic Energy = ½ × mass × velocity² | Potential Energy = mass × gravity × height
Kinetic energy scales with the square of velocity — doubling speed quadruples the energy. This is why speeding dramatically increases stopping distance and crash severity.
Potential energy depends on height. Roller coasters start from the highest point so gravitational PE converts to KE throughout the ride.
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Energy Calculator
Calculate kinetic and potential energy easily
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5. Chemistry: pH & Half-Life
pH
Formula
pH = -log₁₀[H⁺]
pH = negative log base 10 of hydrogen ion concentration (mol/L)
pH measures acidity on a 0-14 scale. pH 7 is neutral (pure water). Below 7 is acidic; above 7 is basic. Each unit represents a 10-fold change in H⁺ concentration.
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pH Calculator
Convert between pH and H⁺ concentration
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Half-Life
Formula
N(t) = N₀ × (1/2)^(t/t₁/₂)
Remaining = Initial × (1/2)^(elapsed time / half-life)
Half-life is the time for a substance to decay to half its original amount. Carbon-14 has a half-life of ~5,730 years, enabling archaeological dating. Caffeine's half-life is about 5 hours — a 3 PM coffee still has half its caffeine at 8 PM.
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Half-Life Calculator
Calculate radioactive decay and half-life
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6. Science in Everyday Life
Cooking & Density
Test egg freshness using saltwater — fresh eggs sink (higher density) while old eggs float (gas buildup lowers density).
Electric Bills & Ohm's Law
Power (W) = V × I. A 1,000W heater running 2 hours = 2 kWh. At roughly 120 KRW/kWh, that's 240 KRW per day.
Driving & Energy
Braking distance is proportional to kinetic energy. Doubling speed quadruples both energy and stopping distance.
Science formulas are powerful tools for quantitatively understanding the world around us. Use CalKit's science calculators to perform calculations effortlessly and build your scientific intuition.