Introduction:
Frictional force is a force that opposes the relative motion or tendency of motion between two surfaces in contact. It acts in the opposite direction of the applied force and can be experienced in various situations. While friction is commonly associated with solid objects in contact, it can also act through air to some extent.

Explanation:
Friction is the result of intermolecular forces between the atoms or molecules of two surfaces in contact. When one surface moves or tends to move over the other, these intermolecular forces create resistance, giving rise to frictional force. While solids have more closely packed molecules, allowing for stronger intermolecular forces and hence greater friction, gases like air also have molecules that can exert a certain amount of resistance.

Example:
Frictional force acting through air:
One common example of frictional force acting through air is the motion of a parachute. When a person jumps from an airplane and deploys a parachute, the large surface area of the parachute encounters the air molecules as it falls. This creates air resistance, which is a type of frictional force acting in the direction opposite to the motion of the parachute.

Explanation:
The parachute experiences air resistance because the air molecules collide with the surface of the parachute. As the parachute moves downward, it pushes the air molecules in its path downward as well. The air molecules exert a force on the parachute, resisting its motion and creating frictional force. This frictional force due to air resistance helps to slow down the descent of the parachute and allows for a safe landing.

Conclusion:
In conclusion, frictional force can act through air, as seen in the example of a parachute. While the magnitude of frictional force through air is generally much weaker than that between solid surfaces, it still plays a significant role in various scenarios. Understanding the concept of friction and its applications can help us comprehend the mechanics of different objects and their interactions with the environment.