The Basic Physics Calculator provides five fundamental physics formulas in one tool.
Velocity (v=s/t), Force (F=ma), Kinetic Energy (KE=half mv squared), Potential Energy (PE=mgh), and Ohm's Law (V=IR). Each formula can solve for any unknown variable.
Calculator information
📋 How to use this calculator
- Select the formula to compute: velocity, force, kinetic energy, potential energy, or Ohm's Law.
- Pick the unknown variable (leave its field blank) and fill in the other variables.
- Use SI units: meters (m), seconds (s), kilograms (kg), newtons (N), joules (J), volts (V), amperes (A), ohms (Ohm).
- Use g = 9.8 m/s^2 for standard gravity, or 9.81 for higher precision.
- Verify the result with dimensional analysis to confirm the units are correct.
- Tip: convert units to SI first (km/h to m/s: divide by 3.6) before plugging into a formula.
🧮 Five fundamental physics formulas
v = s/t; F = m*a; KE = (1/2)mv^2; PE = mgh; V = I*R
- v = velocity (m/s); s = distance (m); t = time (s)
- F = force (N); m = mass (kg); a = acceleration (m/s^2)
- KE = kinetic energy (J); PE = potential energy (J); g = 9.8 m/s^2; h = height (m)
- V = voltage (V); I = current (A); R = resistance (Ohm)
Ohm's Law applies to ohmic conductors at constant temperature; it does not hold for diodes or incandescent bulb filaments.
💡 Worked example: A 1,000 kg car traveling at 20 m/s - calculate kinetic energy
Steps:- Write the formula: KE = (1/2) * m * v^2.
- Compute v^2 = 20^2 = 400 m^2/s^2.
- Compute m * v^2 = 1,000 x 400 = 400,000 kg*m^2/s^2.
- Divide by two: KE = 200,000 J = 200 kJ.
- Dimensional check: kg * (m/s)^2 = kg*m^2/s^2 = joule.
Result: Kinetic energy = 200,000 J or 200 kJ - enough to lift a 4-ton elevator about 5 m.
❓ Frequently asked questions
What is the difference between speed and velocity?
Speed is the magnitude of motion without regard to direction (a scalar), while velocity is a vector that includes direction. A car traveling 60 mph north and one traveling 60 mph south have the same speed but different velocities. The formula v = s/t in introductory physics usually refers to average speed.
Why does gravitational acceleration vary by location?
Gravitational acceleration depends on a planet's mass and radius, so even at Earth's surface it varies from about 9.76 to 9.83 m/s^2 due to rotation, altitude, and local mass distribution. The internationally standardized value (CIPM) is 9.80665 m/s^2, often rounded to 9.8 m/s^2 for classroom work.
How are kinetic energy and momentum related?
Momentum p = mv is a vector quantity, while kinetic energy KE = (1/2)mv^2 is a scalar. They are linked by KE = p^2 / (2m). In collisions, momentum is always conserved; kinetic energy is conserved only in perfectly elastic collisions.
Does Ohm's Law always apply?
No. Ohm's Law V = IR holds for 'ohmic' materials like copper and carbon resistors at constant temperature. For incandescent filaments, semiconductor diodes, or LEDs, the V-I relationship is non-linear and R changes with current. Non-ohmic components are characterized by their experimental I-V curves.
How do I make sure units are correct in a physics formula?
Use dimensional analysis: confirm that the left- and right-hand sides of the equation have the same dimensions after unit substitution. For example, F (N) = m (kg) * a (m/s^2) yields kg*m/s^2, equivalent to 1 newton. Always convert to SI before plugging in numbers.
📚 Sources & references
Last updated: May 11, 2026