How to Use the Physics Calculator
- Choose a formula from Formula / calculation.
- Choose the variable to calculate in Solve for. The selected variable is removed from the input fields.
- Enter the remaining known values and choose a compatible unit where a selector is provided.
- Click Calculate, then review the result and displayed steps.
- Use Copy result or Download result (.txt) to save the output. Use Reset to return to Force mode and rebuild the fields.
Supported Calculations
The calculator has 16 modes. Each mode applies one direct formula and lets you choose which listed variable to calculate.
- Force:
F = m × a - Acceleration:
a = (v − u) / t - Momentum:
p = m × v - Kinetic energy:
KE = ½ × m × v² - Potential energy:
PE = m × g × hwithg = 9.80665 m/s² - Work:
W = F × d × cos(θ) - Power:
P = W / t - Pressure:
P = F / A - Density:
ρ = m / V - Ideal gas law:
P × V = n × R × TwithR = 0.0820573660809596 L·atm·mol⁻¹·K⁻¹ - Ohm's law:
V = I × R - Voltage drop:
V_drop = I × R_wire - Battery runtime:
t = Capacity / Current - Wave speed / wavelength:
v = λ × f - Photon energy:
E = h × fwithh = 6.62607015 × 10⁻³⁴ J·s - Half-life:
N = N₀ × (1/2)^(t / T)
Choosing Variables and Units
Solve for lists the variables available for the selected mode. Applicable known inputs have compatible unit selectors, and the calculator converts those values to the mode's internal base units. The half-life quantities Remaining quantity (N) and Initial quantity (N₀) are unitless, so they do not show unit selectors. The calculated result is displayed in that variable's default unit; there is no result-unit selector.
Input Rules and Validation
Enter ordinary signed decimal numbers only. The parser accepts values matching ^-?\d*\.?\d+$; scientific notation such as 1e3 and comma-formatted values are rejected. Empty fields and invalid text are also rejected. Mode-specific checks require some quantities to be positive, keep temperatures above absolute zero, and prevent a half-life remaining quantity from exceeding the initial quantity. Invalid work-angle combinations and non-finite results are rejected with an error.
Results, Steps, and Reset
The result includes the formula, the entered values in base units, one calculation expression, and the final result. It does not show every intermediate arithmetic operation. Use Copy result to copy the displayed text or Download result (.txt) to save the result and steps as plain text. Reset returns the interface to Force mode and rebuilds its fields.
Constants and Formula Assumptions
Potential energy uses g = 9.80665 m/s². Ideal-gas calculations use R = 0.0820573660809596 L·atm·mol⁻¹·K⁻¹ and the ideal-gas model. Photon energy uses h = 6.62607015 × 10⁻³⁴ J·s. The formulas use the values you enter and do not look up or infer missing values. Battery runtime uses a direct capacity/current relationship.
What This Tool Does Not Model
Each calculation applies one direct algebraic rearrangement. The tool does not model multi-body systems, compound circuits, non-ideal gases, non-linear battery discharge, or other compound systems. Its output is not certified engineering, electrical, or professional analysis.
Privacy and Local Processing
The calculator code processes calculation inputs locally in your browser using fixed formulas. This statement describes the calculator logic only and does not make a broader claim about other page features or site network activity.
Frequently Asked Questions
What calculations does this physics calculator cover?
It covers 16 modes: force, acceleration, momentum, kinetic energy, potential energy, work, power, pressure, density, ideal gas law, Ohm's law, voltage drop, battery runtime, wavelength, photon energy, and half-life.
Can I solve for any variable, not just the one listed first?
Yes. Each mode has a Solve for dropdown listing every variable in that formula. Pick the unknown, enter the remaining known values, and the calculator rearranges the formula to isolate the one you chose.
How does the calculator handle units?
Applicable known inputs have selectors for compatible units, such as Kilograms (kg), Grams (g), or Pounds (lb) for mass and Kelvin (K), Celsius (°C), or Fahrenheit (°F) for temperature. Half-life quantities are unitless. Inputs are converted to internal base units, and the result uses the calculated variable's default unit.
What counts as a physically invalid input?
Examples include zero or negative mass, area, or volume where a positive value is required; a temperature at or below absolute zero; a remaining half-life quantity greater than the initial quantity; and a work-angle combination that implies a cosine outside the range -1 to 1. These are rejected with an error.
Does this tool model complex or multi-body physical systems?
No. Each mode is a single, direct application of one classical formula to the numbers you provide. It does not simulate multi-body systems, circuits with multiple components, non-ideal gases, non-linear battery discharge, or any other compound system, and it is not a substitute for certified engineering analysis.