# Help! I'm confused!

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Since I'm interested in physics, I've been selected to try out for a junior physics team. The problem is that I only just started high school this year. Soo I have no idea what I'm doing.

This is the question:

An apple dropped from a balcony of a multi-story building will calmly

descend into the hands of your friend, if you attach to the apple a

propeller cut out of dense paper. Explain the principle of work for such

a parachute and study the dependence of the drag force on the descent

rate and on the sizes of the propeller's blades.

Please explain this like you would to a 10-year-old.

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The effect in general is called autorotation and it is how an autogyro flies. I would Google it for more info. I imagine Wikipedia and youtube would have lots on it as well.

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An apple dropped from a balcony of a multi-story building will calmly

descend into the hands of your friend, if you attach to the apple a

propeller cut out of dense paper.

Basically, the scenario is you stick a basic helicoptor main rotor-ish paper cut out into it. You let it drop and observe the difference in velocity compared to an apple without a paper rotor blade attachment.

Explain the principle of work for such

a parachute and study the dependence of the drag force on the descent

rate and on the sizes of the propeller's blades.

Now they want you to look at your data and figure out how the paper rotor works. Specifically how do the sizes of the paper rotors affect descent rate and overall lift-to-drag ratio.

I hope someone who has taken a physics course in the last decade can correct any errors.

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The effect in general is called autorotation and it is how an autogyro flies. I would Google it for more info. I imagine Wikipedia and youtube would have lots on it as well.

On the money. Zuni, if you want to actually experiment with it, pay careful attention to what are termed the driving section and driven section of an autorotating rotor. If you mess that up, your rotor will stall, and it won't do anything.

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