They are called pleura. There are 2 membranes, the visceral which is the outer slippery covering, and the parietal which is the inner covering, with a cavity in between them called the pleural cavity
Parietal and visercal pleura are the membrane that surrounds each lung and reduces the friction of breathing.
Pleura
reduces friction
The visceral membrane is a type of serous membrane, which covers the outer layer of organs (such as the intestines). It secretes small amounts of a serous fluid, which reduces friction between organs and other structures.
reduces
speed
Friction.
An aerodynamic shape
no, it just reduces it
Lubbricant
oil in a car's engine reduces viscous friction and wear
It reduces the coefficient of friction.
Graphite
Reduces