* Friction: A force that opposes motion between two surfaces in contact.
* Force: A push or pull that can cause a change in motion.
* Flexural Force: A force that causes bending or flexure in a material.
* Fluid Force: A force exerted by a fluid (liquid or gas) on an object.
Do you have a specific context in mind? Knowing the situation might help me identify the specific "f" force you are looking for.
