How to choose between force, work and energy calculators
These get confused constantly because everyday speech uses them loosely. Force is a push measured in newtons — use the Force Calculator for F = ma. Work only happens when that force moves something through a distance, which is what the Work Calculator computes. Holding a heavy box still involves force but zero work.
Energy is the capacity to do that work, and it comes in forms. The Kinetic Energy Calculator covers motion and the Potential Energy Calculator covers height. Power, from the Power Calculator, is energy per unit time — the rate, not the amount.
When to use Ohm's law and electrical calculators
Reach for the Ohm's Law Calculator whenever you know two of voltage, current and resistance and need the third. It underpins almost every basic circuit question: sizing a resistor for an LED, checking whether a wire will carry a load, or working out why a component is running hot.
Pair it with power. Watts equal volts times amps, so once Ohm's law gives you the missing quantity the Power Calculator tells you what the component must dissipate. For mechanical output, the Horsepower Calculator converts watts into horsepower, and the Efficiency Calculator compares useful output against input.
Getting motion and rotation problems right
Keep units consistent and be careful about vectors. The Velocity Calculator gives speed from distance and time, and the Acceleration Calculator gives the rate of change of velocity — which is non-zero even at constant speed if direction is changing, as in circular motion.
That is exactly what the Centripetal Force Calculator handles: the inward force needed to keep something on a circular path, which rises with the square of speed. For rotating systems, the Torque Calculator multiplies force by lever arm, and the Gear Ratio Calculator shows the trade of speed for torque.
Frequently asked questions
- What is the difference between mass and weight?
- Mass is the amount of matter in an object and does not change with location; weight is the force gravity exerts on that mass, so it changes with gravitational field strength. A 70 kg person has 70 kg of mass everywhere but weighs about 687 N on Earth and roughly a sixth of that on the Moon.
- How do you calculate force?
- Multiply mass by acceleration — Newton's second law, F = ma, with mass in kilograms and acceleration in metres per second squared to give newtons. For an object being lifted against gravity, use 9.81 m/s² as the acceleration.
- What is Ohm's law?
- Voltage equals current times resistance, or V = IR. Rearranged, current is voltage divided by resistance and resistance is voltage divided by current.
- What is the difference between energy and power?
- Energy is a quantity measured in joules; power is the rate of using it, measured in watts, where one watt is one joule per second. A 100 W bulb running for an hour uses 360,000 joules.
- Why does centripetal force increase with speed?
- Because it depends on velocity squared — doubling the speed around a corner quadruples the force needed to stay on the path. That is why cornering speed limits are much lower than straight-line ones and why a tighter radius makes it worse.