Physlink.com published answer: "My son William is doing a science fair project for 6th grade. He tried using different light bulbs to power a solar car. The incandescent bulbs (infrared, regular white and UVA) worked but fluorescent bulbs did not although they had the same light (lumens). He wanted to know why?"

 What a great topic for a science fair project!  To answer the question I want you to think about color.  Which colors have more intensity or are warmer to you? 

 

The nature of color is such that a material will absorb every frequency of color but the one it represents and that frequency will be reflected. Also consider lighter surfaces versus darker surfaces.  A pool deck is painted white to keep it cooler by reflecting all the colors of the spectrum.  A blacktop surface absorbs the energy from all frequencies of light reflecting very little and making it very hot.

 

Now back to the solar car science fair question.  Each of the lights mentioned in the problem had certain characteristics which were being judged for their effectiveness in powering a solar car.  While each light was distinct in spectrum, you need to consider not only which end of the spectrum you were dealing with, but how much or how wide of a spectrum you were dealing with.  Each of the bulbs that worked well with the car represented a wide spectrum of energy.  Even though the IR and UV bulbs are skewed to one end of the spectrum, you have to remember that there is electromagnetic (light) energies that go beyond the visible spectrum of light.  

 

A fluorescent light has a very narrow frequency band of energy.  You may have recognized this as objects look different in its light.  For years homeowners balked at the idea of putting fluorescent lighting in their homes even though fluorescent fixtures use a fourth the energy because it gives a cold look as opposed to the warm look of incandescents.  You may have also noticed fluorescent products such as artificial lighting for plants and aquariums that advertise fuller spectrum energy to enhance color, appearance and growth for these same reasons. You would expect these bulbs to not only give objects in its light better color, but since it is fuller spectrum, your solar car should perform better.

 

There is also higher photonic energy on the infrared side of the spectrum because of its longer wavelength.  If you were to consider all options that light has when striking a solar panel:  It can reflect off of it and not create electricity; it can be absorbed and not create electricity; it can be absorbed and create electricity; and it can pass straight through and do nothing.  The nature of longer wavelength IR light is such that it is more easily absorbed.  On the other hand UV light is higher frequency light and has the tendency to pass through objects rather than be absorbed.  One might expect, depending on the purity of the light source, that the IR bulb did better than the UV bulb.  Additionally, fluorescent bulbs usually tend to be found in the UV side of the light spectrum and so these UV characteristics would apply.

Physlink.com published answer: "What is a fuel-cell and how does it work?"

Perhaps the simplest way to describe the process a fuel cell uses to produce electricity is to compare it to reverse electrolysis. Everyone is familiar with the classic experiment of electrolysis, where direct current is conducted to an anode and a cathode submerged in a liquid high in electrolytes (free ions as from salts for example). The effect is that the electrical energy separates the hydrogen and oxygen with the atoms of oxygen collecting at the anode and the atoms of hydrogen collecting at the cathode.

In a fuel cell, the process is somewhat reversed. Gaseous hydrogen and oxygen flow separately around either side of two electrolytic plates serving as anodes and cathodes. These are separated by a thin polymer membrane which serves as a filter. As free hydrogen and oxygen atoms collect on the plates, they are chemically attracted to each other, but the polymer membrane prevents all but the small hydrogen protons from passing through. The potential created by shearing off the hydrogen proton from its electron is usable electricity and is carried around the membrane in an external circuit. The byproducts of the fuel cell are heat (from the proton electron separation), and water.

It sounds like the greatest thing since sliced bread except there are present limitations: A single fuel cell produces just a fraction of a volt, so many fuel cells must be stacked together to produce the desired amount of electricity; The output of the fuel cell is directly proportional to the purity of the hydrogen. Since it requires more energy to extract pure hydrogen than is produced by the fuel cell, they are impractical as an energy source for most applications; Alternative hydrogen fuel sources for fuel cells, such as methanol, natural gas, or petroleum as more efficient when burned in traditional electrical production methods; Finally, the membrane filter is very expensive because it is platinum covered. The platinum coating acts as a catalyst to induce the disassociation of the hydrogen protons from their electrons to facilitate the electrical potential.

Answered by: Stephen Portz, M.Ed, Technology Teacher, Space Coast Middle School

https://www.physlink.com/education/askexperts/ae376.cfm

Physlink.com published answer: "What are the advantages of ABS braking systems compared to other hydraulic braking systems?"

The advantages of ABS brakes (anti-lock braking system), are just as the meaning of their acronym implies, they eliminate or greatly reduce the possibility of brake lock up and therefore provide a better chance of steering out of trouble.

Conventional hydraulic brakes work by using a cylinder (actuator), which squeezes brake calipers together around the wheel's rotor when the brake petal is depressed. Difficulties arise with these conventional brakes if the road is slick and the driver executes a panic stop. Under these conditions the wheels may lock up and the tires run the risk of losing their grip. When tires lose their grip of the road, there is a good chance that the car may go into an uncontrolled spin. This is why drivers in older vehicles have been taught in the past to pump brakes when on icy roads.

ABS brakes were designed to combat the problem of tire lock up and uncontrolled spins. Since brakes are most effective at slowing the car at a point just before wheel lock up, a system that provides for wheel braking while preventing wheel lock up is very desirable.

Anti-lock brakes do just this by using a computer processor to monitor and control the application of the brakes. At braking, the processor monitors rpm and braking pressure on each of the vehicle's wheels. With this information, measured amounts of pressure are sent to each wheel in the form of hydraulic pulses of pressure to the calipers. These pulses achieve the desired braking pressure without allowing the wheels to lock up.

Answered by: Stephen Portz, Technology Teacher, Space Coast Middle School, FL

Physlink.com published answer: "Is it purely coincidental that the moon rotates on its axis in synch with its revolution around the Earth, keeping the same face always pointed toward us?"

The Earth's moon rotates (spins on its axis), every 27.32166 Earth days. It revolves around the Earth in the exact same period - every 27.32166 Earth days. Because of the synchronization of revolutionary and rotational periods, the same portion of the moon's surface is always directed toward the Earth.

The phenomena of which you speak is not coincidental, and 'universally' speaking, throughout the galaxy, may well be considered more typical of planet moon relationships than perhaps an anomaly.

It is fairly well understood how the gravitational interaction of the moon with our Earth is responsible for the tides on our planet. But far less recognized and understood is the gravitational effects of the Earth on the moon. The mass and speed of rotation of the Earth influence the moon in that some of its rotational energy is actually transferred to the moon. The result of this being that the moon rotation is slowed while also being placed continually into a higher orbit and thus slowing its revolution. The net effect of this gravitational relationship is that the moon's rotation has been slowed to match its orbital period. Ironically, since the Earth is giving up some of its rotational energy to the moon, the Earth and moon will, in the far distant future, reach a synchronization of rotational periods, as Pluto and its nearer to its mass moon Charon have already done.

Many of the moons in the solar system have also reached this point of equilibrium. In Jupiter, the moons Amalthea, Thebe, Io, Ganymede, Callista, and Europa, all have identical rotational and revolutionary periods.

Answered by: Stephen Portz, Technology Teacher, Space Coast Middle School, FL

Physlink.com published answer: "Einstein believed in determinism but the quantum theory disbanded this idea. Do you believe that determinism will be revitalized by the unified field theory? Why or why not?"

 Surprisingly enough the questions that you pose are as much philosophical as they are scientific.  And I am positive that you also understand that these questions can not be answered with what we presently understand about quantum mechanics, unless of course we have discovered our own little unified theory, but it can make for an interesting discussion, so here goes…

 

The statement that you make about quantum theory “disbanding” Einstein’s ideas about determinism is somewhat troubling – since neither quantum point of contention determinance or indeterminance, has been indisputably validated.  So we can’t say that one necessarily trumps another. But, what I think I hear you saying when you mention the unified theory revitalizing thoughts about determinism is that you hold a belief that Einstein will eventually be vindicated for maintaining his determinant position on quantum characteristics.

 

It should be remembered that Einstein largely broke with the great minds of his day as he maintained that "GOD does not play with dice."  The essence of his statement was to say that just because we do not presently have the ability to measure and determine quantum behavior, does not mean that quantum behavior is indeterminate. 

 

These beliefs ran contrary to many of the scientists at the time such as Heisenburg, Schrodinger, and Bohr, who based their belief system of quanta mechanics with theories supporting indetermination.  These scientists and others combined to form what was called the Copenhagen Interpretation of thoughts on quantum behavior which was the largely accepted theory of the time, and in many ways is still maintained today.

 

Heisenburg of course, is famous for the Uncertainty Principle, which states that the simple act of measuring quanta requires an intrusion into its miniscule realm, which in itself invalidates the measurement through the added energy of “looking.”  Schrodinger’s Cat explains determining quantum characteristics in much the same way but with a much more entertaining visual.  A cat locked in a box with a glass vial full of poison gas which will break upon the random decay of some unknown radioactive material.  How would you know if the cat in the box had died or remained yet alive.  You don’t!  You can only know if you open the box and look, but in the act of looking will you accelerate or cause the radioactive decay?  In this way, Schrodinger maintained, the cat can be said to be both dead and alive.  

 

It should be noted that Stephen Hawking’s feelings about these ideas were such that he said that every time he heard the Shrodinger’s Cat explanation for quantum mechanics he wanted to reach for his gun and shoot someone.

 

The basis for stating that your original question is as much philosophical as it is scientific is that it represents a great hold out in the scientific community in the random nature vs order and intelligent design debate.  For some scientists the notion of random patterns of chance as it deals with indeterminism in quanta, is an ontological debate, not just an epistemological debate.  In others words, people feel that we are not just talking about a simple scientific fact, we are dealing with the very fabric of the cosmos and how everything is that is.  One side saying ahh-haa, the universe has random order and can’t be described with an equation. The other side postulating, at least in part, that order would indicate an intelligent design in that all things have a mathematical component or description.

 

It would be naive not to characterize the role that philosophy plays in this specific question as a distinct movement within the scientific community.  Scientific minds in the time of Einstein were desperately looking for breaks from the metaphysical world, or that which was difficult to explain without scientific methods. Describing quantum characteristics in terms of the randomness of nature (indetermination), had a really good secular look and feel about it and was embraced, notwithstanding the criticisms of Einstein, and later, Hawking.  For these reasons, uncertainty as it deals with quantum mechanics is still widely held.   This is not to say that all the proponents of determinism espouse the concept of intelligent design, it is just that they believe that all things may be described mathematically, which definitely hints of order in the universe.  Eventually, when we have the ability to look unintrusively and measure to the degree of sensitivity required to define quanta, they believe it will be revealed that all particles follow an orderly pattern which may be determined with an equation.

 

The suggestion that you make about a unified theory resurrecting determinism may yet prove to be true.  It does seem a little ironic that scientists are looking for the Holy Grail in a unified theory that explains how everything in the universe operates while still espousing the belief that quantum mechanics are indeteminant.

Physlink.com published answer: "Who is the inventor of television?"

 Who is the inventor of television? You have really opened up a can of worms with that question! Probably no other invention in history has been so hotly disputed as the prestigious claim to the invention of 'Tele-vision or 'long-distance sight' by wireless.'

Since Marconi's invention of wireless telegraphy in 1897, the imagination of many inventors have been sparked with the notion of sending images as well as sound, wirelessly. The first documented notion of sending components of pictures over a series of multiple circuits is credited to George Carey. Another inventor, W. E. Sawyer, suggested the possibility of sending an image over a single wire by rapidly scanning parts of the picture in succession.

On December 2, 1922, in Sorbonne, France, Edwin Belin, an Englishman, who held the patent for the transmission of photographs by wire as well as fiber optics and radar, demonstrated a mechanical scanning device that was an early precursor to modern television. Belin's machine took flashes of light and directed them at a selenium element connected to an electronic device that produced sound waves. These sound waves could be received in another location and remodulated into flashes of light on a mirror.

Up until this point, the concept behind television was established, but it wasn't until electronic scanning of imagery (the breaking up of images into tiny points of light for transmission over radio waves), was invented, that modern television received its start. But here is where the controversy really heats up.

The credit as to who was the inventor of modern television really comes down to two different people in two different places both working on the same problem at about the same time: Vladimir Kosma Zworykin, a Russian-born American inventor working for Westinghouse, and Philo Taylor Farnsworth, a privately backed farm boy from the state of Utah.

'Zworykin had a patent, but Farnsworth had a picture''

Zworykin is usually credited as being the father of modern television. This was because the patent for the heart of the TV, the electron scanning tube, was first applied for by Zworykin in 1923, under the name of an iconoscope. The iconoscope was an electronic image scanner - essentially a primitive television camera. Farnsworth was the first of the two inventors to successfully demonstrate the transmission of television signals, which he did on September 7, 1927, using a scanning tube of his own design. Farnsworth received a patent for his electron scanning tube in 1930. Zworykin was not able to duplicate Farnsworth's achievements until 1934 and his patent for a scanning tube was not issued until 1938. The truth of the matter is this, that while Zworykin applied for the patent for his iconoscope in 1923, the invention was not functional until some years later and all earlier efforts were of such poor quality that Westinghouse officials ordered him to work on something 'more useful.'

Another player of the times was John Logie Baird, a Scottish engineer and entrepreneur who 'achieved his first transmissions of simple face shapes in 1924 using mechanical television. On March 25, 1925, Baird held his first public demonstration of 'television' at the London department store Selfridges on Oxford Street in London. In this demonstration, he had not yet obtained adequate half-tones in the moving pictures, and only silhouettes were visible.' - MZTV

In the late thirties, when RCA and Zworykin, who was now working for RCA, tried to claim rights to the essence of television, it became evident that Farnsworth held the priority patent in the technology. The president of RCA sought to control television the same way that they controlled radio and vowed that, 'RCA earns royalties, it does not pay them,' and a 50 million dollar legal battle subsequently ensued.

In the height of the legal battle for patent priority, Farnsworth's high school science teacher was subpoenaed and traveled to Washington to testify that as a 14 year old, Farnsworth had shared his ideas of his television scanning tube with his teacher.

With patent priority status ruled in favor of Farnsworth, RCA for the first time in its history, began paying royalties for television in 1939.

Philo Farnsworth was recently named one of TIME Magazine's 100 Greatest Scientists and Thinkers of the 20th Century.

References:

• The United States Patent Office patent interference #64,027
• The Pioneers of Electronic and Mechanical Television
  by MZTV
• The Birth of Television
  by the VideoUniversity.com
• Who invented television?
  by Paul Schatzkin
• On John Logie Baird
  by Jones Telecommunications & Multimedia Encyclopedia

Answered by: Stephen Portz, Technology Teacher, Space Coast Middle School, FL

https://www.physlink.com/education/askexperts/ae408.cfm

Physlink.com published answer: "How does a cat land on its legs when dropped?"

 Cats have the seemingly unique ability to orient themselves in a fall allowing them to avoid many injuries. This ability is attributed to two significant feline characteristics: A 'righting reflex' and a unique skeletal structure.

The 'righting reflex' is the cat's ability to first, know up from down, and then the innate nature to rotate in mid air to orient the body so its feet face downward. Animal experts say that this instinct is observable in kittens as young as three to four weeks, and is fully developed by the age of seven weeks.

A cat's 'righting reflex' is augmented by an unusually flexible backbone and the absence of a collarbone in the skeleton. Combined, these factors allow for amazing flexibility and upper body rotation. By turning the head and forefeet, the rest of the body naturally follows and cat is able reorient itself.

Reports of cats surviving falls of several stories in height have coined the expression of cats having 'high rise syndrome.' Like many small animals, cats are said to have a non-fatal terminal falling velocity. That is, because of their very low body volume-to-weight ratio these animals are able to slow their decent by spreading out ' flying squirrel style. Simply put, animals with these characteristics are fluffy and have a high drag coefficient giving them a greater chance of surviving these falls.

Answered by: Stephen Portz, Technology Teacher, Space Coast Middle School, FL

https://www.physlink.com/education/askexperts/ae411.cfm