Physics and Chemistry Formulas: Quick Reference for Common Calculations

Essential Physics Formulas

Newton's Second Law: F = ma (Force = mass × acceleration). Units: Newtons (N) = kg·m/s²
Kinetic Energy: KE = ½mv² (m = mass in kg, v = velocity in m/s). Units: Joules (J)
Potential Energy: PE = mgh (g = 9.81 m/s², h = height in meters)
Ohm's Law: V = IR (Voltage = Current × Resistance). Watts = Volts × Amps
Work: W = F × d (Force × distance in same direction)
Power: P = W/t (Work ÷ time) = Watts
Density: ρ = m/V (mass ÷ volume)
Pressure: P = F/A (Force ÷ Area) = Pa (Pascals)

Essential Chemistry Formulas

Molarity: M = moles solute ÷ liters of solution
Ideal Gas Law: PV = nRT (P = pressure, V = volume, n = moles, R = 8.314 J/mol·K, T = Kelvin)
pH: pH = −log[H⁺] (where [H⁺] = hydrogen ion concentration in mol/L)
Percent yield: (Actual yield ÷ Theoretical yield) × 100%

Unit Conversions for Science

1 calorie = 4.184 joules
1 atm = 101,325 Pa = 14.696 psi
0°C = 273.15 K; K = °C + 273.15
1 mole = 6.022 × 10²³ particles (Avogadro's number)

Frequently Asked Questions

What is the difference between mass and weight?

Mass is the amount of matter in an object (kg) — constant regardless of location. Weight is the gravitational force on that mass (Newtons = mass × g). On the moon (g ≈ 1.62 m/s²), you weigh 1/6 as much as on Earth but have the same mass. In everyday use, 'weight' usually means mass in kg.

How do I convert between Celsius and Kelvin?

K = °C + 273.15. Kelvin is the SI unit of temperature with absolute zero (0 K = −273.15°C) as its reference point. All thermodynamic calculations require Kelvin — never plug Celsius into gas law equations.