A flying object requires force to overcome air friction, also known as air resistance or drag, because air resistance opposes the motion of the object through the air. When an object moves through a fluid, such as air, the fluid exerts a force on the object in the opposite direction to its motion. This force of air resistance increases with the speed of the object.
There are several reasons why air resistance affects a flying object:
Fluid Dynamics: Air resistance is a consequence of the interaction between the flying object and the air molecules. As the object moves through the air, it collides with the air molecules, causing them to exert a force on the object. These collisions and interactions lead to the generation of air resistance.
Drag Force: The force of air resistance is often referred to as drag. It acts in the direction opposite to the motion of the object. The magnitude of the drag force depends on various factors, including the shape and size of the object, the density of the air, and the object's speed. As the speed of the object increases, the drag force also increases.
Energy Dissipation: Air resistance converts some of the object's kinetic energy into other forms of energy, such as heat or sound. This conversion results in a loss of energy, which means the flying object needs to continually exert force to maintain its speed and overcome the resistance.
Limiting Maximum Speed: Air resistance becomes more significant as the speed of the object increases. At a certain point, the drag force becomes equal to the force propelling the object forward (such as thrust from an engine or the force generated by wings), leading to a balance between the forces. This balance sets a maximum speed for the object, known as the terminal velocity. To overcome air resistance and reach higher speeds, the object must generate additional force.
In summary, air resistance or drag opposes the motion of a flying object through the air. To overcome this resistance, the object needs to generate additional force, either through propulsion systems like engines or by manipulating airflow using aerodynamic designs such as wings or streamlined shapes. By exerting force to counteract air resistance, the flying object can maintain its speed or accelerate in the desired direction.