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College Physics (Urone)
Found in: Page 354

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Short Answer

Helicopters have a small propeller on their tail to keep them from rotating in the opposite direction of their main lifting blades. Explain in terms of Newton’s third law why the helicopter body rotates in the opposite direction to the blades.

According to Newton's third law, every action has an equal and opposite response.

When the propeller of a helicopter begins to spin, the helicopter's body follows the law and attempts to spin in the opposite direction.

See the step by step solution

Step by Step Solution

Step 1: Definition of the force

The push or pull on a mass item that causes it to alter velocity is called force (to accelerate).

Step 2: Rotation of helicopter & Newton’s third law

The main rotors, also known as main rotating blades, are horizontal propellers that raise the entire system. Torque is the force that causes it to rotate. It emanates from the helicopter's engine.

When the blades rotate in one direction, a reaction torque is created that opposes the blades' rotation. If the force rotates the rotor blades clockwise, the engine should experience an equal and opposite counterclockwise force.

As a result, the helicopter's body will also revolve counterclockwise. Finally, the body of the helicopter tries to spin. Newton's third law explains this quite well.

When the helicopter is on the ground, friction (another force) prevents it from rotating; but, once in the air, there is no opposing force, and the body spins in the opposite direction as the rotor blades.


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