Final answer:
Helicopters have a small propeller on their tail to prevent them from rotating in the opposite direction of their main lifting blades. This is due to Newton's third law of motion.
Step-by-step explanation:
Helicopters have a small propeller on their tail to prevent them from rotating in the opposite direction of their main lifting blades. This is due to Newton's third law of motion, which states that for every action, there is an equal and opposite reaction. As the main rotor blades rotate and generate lift, an equal and opposite torque is produced, causing the helicopter body to want to rotate in the opposite direction. The tail propeller produces a counteracting force that stabilizes the helicopters