Final answer:
The horizontal component of lift is the force that enables an airplane to turn when it banks its wings.
Step-by-step explanation:
The force that makes an airplane turn is the horizontal component of lift. When an airplane banks, it does so by tilting its wings, which changes the direction of the lift force. Normally, lift acts vertically to counteract the weight of the airplane, but when banking, the lift force is tilted and can be decomposed into two components: a vertical component that continues to balance the airplane's weight and a horizontal component that is unbalanced and accelerates the airplane in the direction of the turn. The banking angle, represented by θ in physics diagrams, plays a crucial role in determining the magnitude of these components. This concept is analogous to how birds and helicopters create lift and follows Newton's Third Law of Motion, whereby an equal and opposite reaction is experienced.