Physics 11 · Physics · Lesson 4.2
The Second Law (F = ma)
- Level
- Grade 11
- Reading time
- 10 min reading
- Review
- Last reviewed 2026-09-03
- Standard
- Accuracy standard
- Errata
Abstract
Force, mass and acceleration.
What is Newton’s second law of motion?
Short answer
Newton’s second law states that the acceleration of an object is directly proportional to the net force on it and inversely proportional to its mass: F = ma. A larger net force produces a larger acceleration, while a larger mass resists acceleration. Force is measured in newtons (N), where one newton accelerates one kilogram at one m/s².
Concept preview
What you will be able to do
- 01State Newton's second law F_net = ma
- 02Relate net force, mass and acceleration
- 03Solve F = ma problems using the net force
If the first law tells you when motion changes, the second law tells you by how much — and it's the single most useful equation in physics: the net force on an object equals its mass times its acceleration, . Read it three ways and you own it: (1) more net force → more acceleration; (2) more mass → less acceleration for the same force; (3) rearranged, .
School Plan
The Second Law (F = ma)
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Related topics
Frequently asked questions
- What is net force?
- The single force equivalent to all forces acting on an object added together as vectors; only the net force produces acceleration.
- What is one newton?
- The force that gives a 1 kg mass an acceleration of 1 m/s²: 1 N = 1 kg·m/s².