Flying

In the previous lesson I had mentioned gravity (Gravity is the force of attraction between all objects that tends to pull them toward one another) and the need to overcome it when flying. If flying were as simple as getting on a broomstick and flying, muggles would have figured it out hundreds of years ago. However, it took until just a little over one hundred years ago for 2 bothers in North Carolina to figure out how to fly.

When an airplane is flying, the plane pushes the air out of its way. This air is deflected either over the top of the plane or over the bottom of the plane. The simplest way to explain how this helps a plane fly is that the air moving over the top of the plane travels faster than the air moving over the bottom of the plane. This creates enough lift and drag to keep the plane in the air.

Lift…”Lift is the aerodynamic force that holds an airplane in the air, and is probably the trickiest of the four aerodynamic forces to explain without using a lot of math. On airplanes, most of the lift required to keep the plane aloft is created by the wings (although some is created by other parts of the structure).” www.howstuffworks.com”>www.howstuffworks.com

Drag…”Drag is an aerodynamic force that resists the motion of an object moving through a fluid (air and water are both fluids). If you stick your hand out of a car window while moving, you will experience a very simple demonstration of this effect.” www.howstuffworks.com”> www.howstuffworks.com

Remember Newton’s 3 Laws of motion?
1. A body in motion will stay in motion unless acted on by an outside force.
2. Force is equal to mass multiplied by acceleration. (F=ma)
3. Every action has an equal and opposite reaction.

The third law can be applied here. On the wings, the air traveling above and below them is creating an equal, but opposite force. This force kind of makes the plane float in the air. However, we must distinguish that the force on the bottom is not the same as the force acting on the top of the plane. When it’s climbing or descending to a location the angle at which the air is attacking the plane helps it stay on course.

Ok, so if a plane can do it, why can’t a broom? One answer is a plane doesn’t have the same geometry on the top and bottom thus creating the difference in force and air movement over the body of the plane. All the brooms I’ve seen are very similar if not identical on the top and bottom of them, if you can even tell which is the top and which is the bottom. The air would be flowing at the same speed on top and bottom and not giving the broom the proper lift and drag.

Of course flying would be easier if we could flip a switch and turn off gravity. Is this even possible? Well, not really. Scientists have tried. In 1992 Evgeny Podkletnov created a superconductor 145 millimeters in diameter and 6 millimeters thick in which when it started to rotate due to the electric current running through it, it reduced the weight of the object in it by 2 percent, not enough for that object to start floating.

Around 1842 a man by the name of Samuel Earnshaw stated that it is impossible to create levitation using stationary magnets. However, an inventor by the name of Roy Harrigan devolved a toy called the Levitron and defied Earnshaw’s theory. Do you remember paying with magnets? Whenever you put two south poles or two north poles together they repel. This is the same principle by which levitation happens.

A scientist in Holland by the name of Andrey Geim, working with a team of 2 others, was able to levitate a frog by using the magnetic force to his advantage. The magnets used to levitate the frog were up to 100 times stronger than the magnets on your refrigerator. This team also tried fish, mice and plants. The reason this worked is because of a form of magnetism called diamagnetism. “Diamagnetism is a very weak form of magnetism that is only exhibited in the presence of an external magnetic field. (Definition from http://en.wikipedia.org/wiki/Main_Page)

Although science has made breakthroughs, I wouldn’t go buy a Firebolt just yet. These experiments have been done on a small scale. In order to levitate a human, think how big you would have to make the magnets.

Assignment:

1. Who were the brothers that were first to fly an airplane and where did they do it? (4 pts)

2. Name at least 5 models of broomsticks. (2 pts each)

3. What would you say if you wanted to levitate an object? (1 pt)

5. Name 5 forms of transportation used in the wizarding world besides a broomstick. (2 pts each)

6. Research a little more about the instances of levitation I discussed or other instances you know of. Then write a short essay, at least 200 words, on what you found. You must include all sources used. (20 points)

7. For questions 2 and 5 give me more examples of broomsticks and/or forms of transportation. (2 pts each)

8. Who is Bernoulli and why is he important to flying? (10 pts)

You may receive more than 50 points this month for your homework but remember you may not go over 200 points for the term and you need 100 points to earn a quill.

Useful sources for completing your homework are:

HP Lexicon

How Stuff Works

Email the assignment to professornoodle@gmail.com by October 31st. Remember to include the class name in the subject live of your email your HOL ID in the email. Also I will not accept homework sent as an attachment.