Final answer:
Air resistance, or drag force, opposes the motion of objects through a fluid. The drag force depends on the object's speed and surface area. The faster the object moves and the larger its surface area, the greater the drag force.
Step-by-step explanation:
Air resistance, also known as drag force, affects the motion of an object by opposing its motion through a fluid (air or liquid). The drag force depends on the object's speed and surface area. When an object moves faster, the drag force increases. Additionally, the drag force is larger on objects with greater surface area.
For example, if you drop a tennis ball and a hard baseball at the same time, the tennis ball will reach the ground after the baseball because air resistance slows it down more due to its larger surface area. Similarly, a larger object with the same shape will experience more drag force than a smaller object with the same shape.