Icarus, the Ornithopter and Upward

The Ancient Greek legend of Icarus is one of the first examples of humans dabbling with flight, and unfortunately, paying a steep price for it. (Icarus, along with his father Daedalus, built wings from feathers and wax to escape captivity, and succeeded in flying. However, Icarus flew too near the sun, melting the wax that kept the wings together. He then fell to his death, much to the grief of his father :[ ).

Since Icarus, people have kept trying to experiment with attaching wings to themselves like birds, but unlike Icarus, this does not work in real life. Humans do not have the muscle strength that birds have to make wings successful. 

Around 400 BC in China, kites were being made as humans continued to experiment with flying. Kites are the predecessors of gliders and balloons made for flight. 

Then came Leonardo da Vinci with inventions totally ahead of his time, one of which was the Ornithopter. This was one of the first actual flying machines for humans, with two wings and a tail, in the center of which lies the person holding onto handles and stirrups for their feet, with a ring around the torso:

In 1783, Jacques and Joseph Mongolfier filled a silk bag with hot air so that it floated. Eventually, they attached a basket and the first flight in a hot air balloon was taken by a sheep, a rooster and a duck, at an altitude of 6000 feet for a distance of nearly a mile. :) After that was the first manned flight in a hot air balloon. 

George Cayley, in the late 1700s to mid 1800s, began a detailed study of gliders that allowed the person flying it to control its movements. He modified the wings so that air flowed over them more effectively, and added a tail for stability. He also realized that for longer flights, a power source would be needed. Cayley concluded that the best type of flying machine for a human would be a "fixed-wing aircraft with a power system for propulsion and a tail to assist in the control of the plane".  

By the nineteenth and twentieth centuries, more and more scientists were experimenting with flight. The German engineer Otto Lilienthal was fascinated by and studied birds and flight. The Wright brothers based some of their work on Lilienthal's studies. Unfortunately, after more than 2500 flights, Lilienthal was killed when he lost control due to a sudden gust of wind and crashed to his death. 

Flight among humans further progressed with Samuel Langley and his aerodrome, which included a steam powered engine which he realized was needed if humans wanted to fly for longer distances.

And finally, here are the Wright brothers. Through a lot of research and background knowledge, Orville and Wilbur Wright first experimented with balloons and kites, then gliders, and then the shapes of wings and such in wind tunnels. Then they began to create an engine that would propel the plane. From all this, they made the Flyer, which on December 17 1903, piloted by Orville Wright, became the first controlled, powered flight that was heavier than air. 

And from the Wright brothers, humans really went...upward!

Sources: http://www.ueet.nasa.gov/StudentSite/historyofflight.html , http://cache2.artprintimages.com/p/LRG/15/1501/U2BBD00Z/art-print/bernard-picart-the-fall-of-icarus-1731.jpg , http://images.elfwood.com/art/l/e/lexilane21/icarus_72.jpg , http://seerpress.com/wp-content/uploads/2010/09/ornithopter.jpg , http://www.aps.org/publications/apsnews/200611/images/balloon.jpg , http://www.century-of-flight.net/Aviation%20history/aviation%20timeline/images2/10.jpg , http://www.ueet.nasa.gov/StudentSite/images/flight/glider-2.jpg , http://www.flyingmachines.org/aerd4a.jpg , 

http://www.aviation-central.com/famous/images/ab1a0-ol.gif , http://www.nasa.gov/images/content/206308main_image_976_946-710.jpg

My Unanswered Magnetism Questions--Answered!

After asking my older sister, (who demonstrated knowledge about high school-level magnetism that even she didn't know she had) I have the answers to my questions!! XD

Now answered Question 1: What is the difference between magnetic lines of force and magnetic field lines?

Answer: Actually, there is no difference. The arrows on magnetic field lines represent the direction of magnetic force at that point in the field (the magnetic force is the force that causes something, like an iron filing or a compass needle, to move because of a magnetic field). So, magnetic field lines are lines of force as well.

Now answered Question 2: What is meant by the magnetic field is "cancelled out"?

Answer: "Cancelling out" a magnetic field does not mean there is no magnetic field there. It simply means that because the two interacting magnetic forces (the arrows on field lines) are equal but in opposite directions, so the net magnetic force at that point is zero. If a compass needle, for example, was put at a point like this, it would experience equal pull in opposite directions. Therefore, it would not move.

Now answered Confusing Part about Declination: How can the angle be different at different places?

Answer: Looking at the picture below and listening to my sister, I realized that while the compass needle will swing towards the magnetic north pole from any point on the Earth, true north is always just straight up. I thought that the angle was between a line drawn to the magnetic north pole and a line drawn to true north, but it's really just between a line drawn to the magnetic north pole and a line drawn straight up. 

Sources: My sister, and the image, which comes from http://en.wikipedia.org/wiki/Magnetic_declination

Some Final Questions on Magnetism

So, because of my test on magnetism tomorrow ( D: ),  I have a list of questions about magnetism that came up as I was going over the concepts again. Here they are in case anyone had these questions/just to help me clarify them to myself.


Question 1: What is the angle of declination and the angle of inclination?

Answer: The angle of declination is the angle between true north or geographic north, and magnetic north. Depending on where you are on the Earth, this angle can differ a lot. For example, one not-very-recent statistic states that Eureka, NWT, has an angle of declination of 98 degrees (the magnetic north pole is at 98 degrees to true north there). On the other hand, Churchill, Manitoba, has an angle of declination of 0 degrees, meaning at Churchill magnetic north and true north are in line with each other. To be honest, I'm not too sure how this works.
             The angle of inclination is the angle between the surface of the Earth and the Earth's magnetic field. At the equator, the magnetic field is parallel to the Earth's surface, but near the poles the magnetosphere :) is at a steep angle to the Earth's surface. Right at the poles, the magnetic field and the Earth's surface are perpendicular to each other. Angle of inclination is measured through a dip needle.


Question 2: What is domain theory?

Answer: Domain theory is a theory that explains certain properties of ferromagnets (materials that magnetize extremely well). The theory states that ferromagnets have inside them tiny regions of atoms that are all oriented the same way, so that they have a north and south pole. Generally, these domains are all oriented randomly to each other, so they have a net magnetic effect of zero. However, with a strong enough external magnetic field (such as a coil with current flowing through it), these domains can be aligned to give us one overall north and south pole. If the magnetic field is increased, the domains will become more aligned. There is a point, though, when the domains cannot be aligned any further. Logically, this makes sense.


Question 3: What does domain theory prove?

Answer: Domain theory conveniently explains...

• why ferromagnets can become magnetized after stroking with another magnet (a big example of this would be ships and buildings becoming magnetized during construction as a result of the Earth's magnetic field)
• why a broken magnet becomes two smaller magnets, not just a north pole and a south pole
• why a strong magnetic field in the opposite direction can switch the poles of a magnet

It also explains how magnetic properties can be lost through heating or dropping a magnet: this jostles the orientation of the domains enough that they resume their random orientation.

For a more in-depth look at domain theory, among other things, go here: Magnets, Magnetism and the Magnetic Field


I actually had some other questions too...but I don't know all their answers.

Unanswered question 1: Is there any difference between magnetic lines of force and magnetic field lines?

Unanswered question 2: If we say that the magnetic fields were cancelled out, does that mean there isn't any field there anymore?

If I find the answers, I will try to blog them. :)

Kinematics and Motion Homework

Question 45: "If a sprinter accelerates at 2.2 m/s^2 for 2.5 s, what is her velocity after this time, assuming initial velocity is 0?"

Answer: I chose to substitute the values into Mommy because that equation had all the values I had and needed. I just isolated final velocity and solved for it. Easy.

Question 47: "A fastball pitcher can throw a baseball at 100 km/h. If the windup and throw take 1.5 s, what is the acceleration of the ball?"

Answer: It took me a while to come up with this answer, because at first I didn't get that by throw, they meant the ball only moves for 1.5 seconds. After that, using Mommy (her smile gets bigger and bigger, I swear), substituting values, and remembering to convert to m/s wasn't so bad.

Question 56: "A car travelling at 40 km/h accelerates at 2.3 m/s^2 for 2.7 s. How far has it travelled in that time? What is its final velocity?"

Answer: At first I got this wrong because I accidentally did the next question, which was the exact same thing but with -2.3m/s^2. Also, it doesn't matter afterward whether you use girl or boy because you have the values for and can find your values through both, but I chose the boy because the girl is used more often in these questions. Give him a chance. 

Question 58: "If 100m sprinters accelerate from rest for 3.5s at 2.8m/s^2, how far have they run to this point? How long will it take them to complete the 100m sprint, assuming they maintain their speed the rest of the way?"

Answer: I did the beginning right initially, but made a mistake later because I didn't realize the sprinters had stopped accelerating. Oops. But the answer below is right.

Question 60: "An object is thrown up from a cliff at 10 m/s and reaches a velocity of 20 m/s down as it lands. If the acceleration due to gravity is 9.8 m/s^2, what is the object's displacement? How long did it take the object to land from the time it was thrown up?"

Answer: This involves vector adding. Basically we can assume that up is the positive direction and down is the negative direction. Then the velocities are 10 m/s and -20 m/s. Also, Daddy finally comes back into the picture :) !

The Graff Family

Well now apparently we have to blog today's homework (which is a lot of work in my opinion: figuring out the questions + what you did wrong + writing them all out nice and big + taking photos + importing them + inserting them + thinking of what to say in this blog...but I'm not complaining ;] ). It's page 71 to 72 in the textbook, #45, 47, 56, 58, and 60.

Now to the more interesting stuff. Today we learned about the Graff family (it's a real name by the way, as in Steffi Graf, the famous tennis player, but with two F's). Their name rhymes with Graph for a reason, but even so call them the Graff's : they hate being called Graphs. Another name for them is the Big Five.
Anyway, Mommy (or ze maza) and Daddy (or ze faza) Graff both come from or are derived velocity-time graphs. Maybe I will blog about how some other time. The rest of the family are derived from Mommy and Daddy. This I may also blog at that other time.

That's ze faza aka Daddy Graff. The block under his eyes are supposed to be a mustache, and the v's are supposed to be vectors. My bad.

Now Daddy and Mommy are together. Mommy has very curly hair. I also forgot one of her vectors for initial velocity. Careless mistake.

Next come the twins: a girl and a boy. They're very similar...even their hair is almost the same. He only lacks three of the things she has: another X-chromosome, a bow, and a value for initial velocity.

Now we have Baby Graff. The baby is a little weird...it actually has no vector signs...sorry...but together they make the whole family !

Notice that each of the family members (equations) is missing one value. For example, Mommy has no displacement, while Daddy has no acceleration. This means they need to work together to solve your problems.

*Every d is really supposed to have a delta symbol in front of it, because displacement is a difference. Here it's not written; it's understood to be there.