Mechanics · Forces & Newton's laws
Chapter 1 · 3
The idea
Friction
Friction as a force opposing motion, with magnitude up to a maximum F ≤ μR (and F = μR at the point of slipping) — on rough horizontal surfaces and slopes, the angle of friction tanα = μ, and F = ma with friction included.
A full journey — read it, play with it, work it, then earn real exam marks. Everything stays on the timeline below.
In this lesson — start anywhere
Mechanics · Forces & Newton's laws
Friction
Friction as a force opposing motion, with magnitude up to a maximum F ≤ μR (and F = μR at the point of slipping) — on rough horizontal surfaces and slopes, the angle of friction tanα = μ, and F = ma with friction included.
Why it works
As big as needed, up to a limit
Real surfaces are rough: they resist sliding with a friction force. Friction is not a fixed amount — it is exactly as big as it needs to be to prevent motion, up to a limit:Friction always acts to oppose the motion (or the direction the body is trying to move).
Keep reading — free
The rest of the explanation, plus 3 worked examples you step through move by move.
Start freeTakes a minute — no card.