# What is the difference between 'Dynamic Friction' and 'Static Friction' in Rigid Body Material?

Hi Forum,

We are wondering if the Dynamic Friction and Static Friction properties for a Rigid Body Material are the same as the physical properties described below, can you help us understand?

Static friction is the force that prevents an object from starting to move, while dynamic friction is the force that resists its motion. Static friction, also known as starting or limiting friction, is the frictional force that must be overcome to set an object at rest into motion.

How is this translated into Isaac Sim?

Hi,

I am moving your topic to the Isaac SIM category for better visibility.

Raffaello

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Thanks for moving it. Is it possible to shine some light on this?

Since the simulation used is PhysX SDK, these values are directly set to PhysX SDK. The PhysX SDK documentation says:

``````Friction uses the coulomb friction model, which is based around the concepts of 2 coefficients: the static friction coefficient and the dynamic friction coefficient (sometimes called kinetic friction). Friction resists relative lateral motion of two solid surfaces in contact. These two coefficients define a relationship between the normal force exerted by each surface on the other and the amount of friction force that is applied to resist lateral motion. Static friction defines the amount of friction that is applied between surfaces that are not moving lateral to each-other. Dynamic friction defines the amount of friction applied between surfaces that are moving relative to each-other.
``````

Does this help?
Regards,
Ales

Hi Ales, just formatting it here to make it easier to read, will get back to you whether it answers the original question :)

Friction uses the coulomb friction model, which is based around the concepts of 2 coefficients: the static friction coefficient and the dynamic friction coefficient (sometimes called kinetic friction). Friction resists relative lateral motion of two solid surfaces in contact. These two coefficients define a relationship between the normal force exerted by each surface on the other and the amount of friction force that is applied to resist lateral motion. Static friction defines the amount of friction that is applied between surfaces that are not moving lateral to each-other. Dynamic friction defines the amount of friction applied between surfaces that are moving relative to each-other.

This answers the original question, thank you!

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