In a free-body diagram, air resistance acting on an object moving through the air is best classified as which type of force?

• A. A normal force exerted by a surface perpendicular to the object’s motion
• B. A long-range gravitational force exerted by Earth regardless of the object’s motion
• C. A frictional (drag) force exerted by a fluid that opposes the object’s motion
• D. A tension force transmitted through a rope or cable attached to the object

Answer: (C)

Verified step by step guidance

1. Understand the nature of air resistance: it is a force that acts opposite to the direction of an object's motion through the air.
2. Recall the types of forces commonly represented in free-body diagrams: normal force, gravitational force, frictional force, tension force, etc.
3. Identify that normal force acts perpendicular to surfaces and does not oppose motion through a fluid like air.
4. Recognize that gravitational force is a long-range force acting downward due to Earth's mass, independent of the object's motion through air.
5. Conclude that air resistance is best classified as a frictional (drag) force exerted by a fluid (air) that opposes the object's motion.