Physics units & constants
Keep units consistent within a calculation. Most experiments use SI units; the lens explorer uses centimetres for every length, and angle inputs are labeled in degrees.
| Quantity | Unit | Symbol |
|---|---|---|
| Position, distance, wavelength | metre | m |
| Time, period | second | s |
| Mass | kilogram | kg |
| Velocity | metres per second | m/s |
| Acceleration | metres per second squared | m/s² |
| Force | newton | N = kg·m/s² |
| Energy, work | joule | J = N·m |
| Power | watt | W = J/s |
| Frequency | hertz | Hz = 1/s |
| Voltage | volt | V |
| Electric current | ampere | A |
| Resistance | ohm | Ω = V/A |
| Spring stiffness | newtons per metre | N/m |
Gravity in this lab
Earth’s gravitational acceleration is modeled as 9.81 m/s². The projectile and pendulum tools let you change it. The Moon preset uses 1.62 m/s². Practice questions explicitly state when they use the convenient approximation g = 10 m/s².
Degrees and radians
One full turn is 360° or 2π radians. The controls accept degrees where labeled; the models convert to radians before evaluating sine and cosine. Refractive index, friction coefficient, and magnification are dimensionless.
Prefixes worth remembering
1 L = 0.001 m³; 1 km = 1,000 m; 1 cm = 0.01 m; 1 mm = 0.001 m; 1 mA = 0.001 A; 1 kΩ = 1,000 Ω. Convert before substituting into a formula.
Find a formula ↗