From 8fa56338b808289e029901bdd13bdd19a8ac7b78 Mon Sep 17 00:00:00 2001 From: eggy Date: Sat, 24 Oct 2020 14:16:54 -0400 Subject: [PATCH] phys: add friction --- docs/sph3u7.md | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/docs/sph3u7.md b/docs/sph3u7.md index aac890b..96ce222 100644 --- a/docs/sph3u7.md +++ b/docs/sph3u7.md @@ -345,10 +345,13 @@ Contact (the two objects are touching) forces: - **Drag** ($\vec{F_D}$) is the resistive force caused by fluids in the path of an object. Its vector is always pointing in the opposite direction of the object's *instantaneous* velocity. - **Thrust** ($\vec{F_T}$) is the propulsive force caused by mass (usually fluids) being ejected from an object. The force vector always points opposite the direction of the ejected mass. -!!! note - Static friction is always equal to the force applied by another object until an object begins to slip, at which point kinetic/dynamic friction applies. Kinetic friction is a constant force that is lower than the peak force of static friction. - - (Source: Kognity) +### Friction + +Static friction is always equal to the force applied by another object until an object begins to slip, at which point kinetic/dynamic friction applies. Kinetic friction, also known as **dynamic friction**, is a constant force that is lower than the peak force of static friction. + +The **coefficient of friction** ($\mu$) represents the ratio between friction force and normal force, and has a different value for kinetic and static friction. The **maximum** force of static friction is equal to its coefficient multiplied by the normal force ($|F_{fS}|_{\max} = \mu_s F_N$), while the force of kinetic friction is equal to its coefficient multiplied by the normal force ($F_{fK} = \mu_k F_N$). + +(Source: Kognity) Non-contact forces: