Every time you push a door, kick a football, or lift a schoolbag, you are applying a Force. But how do scientists measure exactly how much push or pull is being applied? They use a specific scientific unit.
The force of gravity on a standard apple is approximately 1 Newton — which is exactly why the falling apple is so famously linked to Newton's discovery of gravity!
The SI (International System) unit of force is the Newton, abbreviated as N.
It is named after the legendary physicist Sir Isaac Newton, who discovered the laws of motion and gravity.
From Newton's Second Law of Motion: F = ma (Force = mass × acceleration)
1 Newton is defined as the amount of force required to give a mass of 1 kilogram an acceleration of 1 metre per second squared.
1 N = 1 kg·m/s²
Force is a **vector quantity** — it has both magnitude (how much) AND direction (which way). You must always specify both to fully describe a force.
SI Unit of Length
The SI unit of length is the metre (m). Defined as the distance light travels in vacuum in 1/299,792,458 seconds. Learn prefixes: km, cm, mm, nm, Å.
SI Unit of Pressure
The SI unit of pressure is the Pascal (Pa). 1 Pa = 1 N/m². Atmospheric pressure = 101,325 Pa. Learn formula, dimensional formula, and unit conversions.
SI Unit of Resistance, Resistivity, and Capacitance
Learn the SI units of electrical resistance (Ohm), resistivity (Ohm-meter), and capacitance (Farad). Understand their definitions and formulas.
SI Unit of Resistivity — Ohm-Metre (Ω·m)
The SI unit of resistivity is ohm-metre (Ω·m). Derived from ρ = RA/L. Definition, formula, dimension, and resistivity values of common materials explained.
What is the SI Unit of Time?
Learn the SI unit of time. Understand why the Second (s) is the universal standard for measuring time and how it is scientifically defined.
Turn this guide into revision flashcards, a practice exam, or an AI-generated podcast — free, no signup required.