Answer to Question #286636 in Physics for Bea

Question

1. Every weekend, you and your family always find time to bood with each other. All of your family members are fully vaccinated, and they decided to have a two days vacation in Cebu City. You choose to ride a private helicopter towards your destination. You noticed that the helicopter has two sets of lifting blades, they rotate in opposite directions (and there will be no sail propeller). Explain why it is best to have the blades rotates in opposites directions.

2. When you start the enige of your car with the transmission in restral, you notice that the car rocks in the opposite sense of the engine's rotation. Explain in terms of conservation of angular momentum. Is the angular momentum of the car conserved for long (for more than a few seconds)?

3. In a playground, there is a small merry-go-round. Suppose a child walks from the outer edge of a rotating merry-go-round inside, does the angular velocity of the merry-go-round increase, decrease or remain the same? Explain your answer.

Answer 1

1. Because such a configuration of blades helps the helicopter to turn and fly straight.
2. The angular momentum is conserved, so, the car 'trues' to move accordingly.
3. The angular velocity decreases because the moment of inertia decreased as the girl moved toward the center.