Core formulas
- Force: mass x acceleration.
- Work: force x distance when force acts in the direction of movement.
- Kinetic energy: 0.5 x mass x velocity squared.
- Ohm's law: voltage = current x resistance.
Unit consistency
SI units keep formulas clean: kilograms, meters, seconds, newtons, joules, amperes, volts and ohms. If a calculator accepts other units, it should convert them before calculating.
Common mistakes
- Entering weight where the formula expects mass.
- Using kilometers per hour directly in a meter-per-second energy formula.
- Ignoring direction when force and motion are not aligned.
- Treating ideal formulas as full engineering models.
Useful calculators
FAQ
Why do physics calculators care so much about units?
Many formulas assume SI units. Unconverted units can change the result by large factors.
Is weight the same as mass?
No. Mass is the amount of matter; weight is force due to gravity.
Are these formulas enough for engineering design?
No. They are educational estimates and do not replace full engineering analysis.
Named quantities and units
Force is measured in newtons, work and energy in joules, power in watts and pressure in pascals when using SI units. A Formula notes name these units because the arithmetic is only meaningful when units match.
Concrete scenario
A 10 kg mass accelerating at 2 m/s^2 has force of 20 N. If that force acts over 5 m in the direction of motion, work is 100 J. If the work is done in 4 seconds, power is 25 W.
Model limits
Friction.
Air resistance.
Heat loss.
Changing acceleration.
Direction of force.
Material deformation.
Electrical and structural safety requirements.
Last reviewed: 2026-05-14.