01/11/2011

 

Today, our topic was energy: what it is, why we need it, and where we get it. Please read the summary below and the homework assignment at the bottom.

 

Among many other things, we will need energy for heating, machinery, transportation, and recycling. In other words, we need energy to perform work. In physics, the amount of work is a quantity defined as a product of the distance an object moves and the force applied to the object to move it. The objects here may be anything from furniture to electrons. It can be written as

 

 

where W is the work, F is the force, and D is the distance.

 

Energy is an ability to perform work. Importantly, the energy is conserved. If one object performs work on another, the energy of the first one decreases exactly by the amount of the work performed, and the energy of the other increases by the same amount. We discussed a ball that rolls down from a hill, when the force of gravity performs work on it, so the ball accelerates. The energy of motion (called kinetic energy) can be used to perform work, so when the ball hits another ball, so the first ball stops and the second one starts to move. The other ball stops moving when all its kinetic energy is used up against gravity when it rolls up to a second hill. The ball on the top of the hill has the potential to perform work and therefore possesses energy, even though it does not move. This kind of energy is called potential energy.

 

 

If the energy is conserved, why do we need to produce it all the time? The answer is that not all energy can be used to perform work. Due to all kinds of friction, the energy eventually turns into heat, which is disorganized motion of atoms and molecules. They would collide and perform work on each other, but we cannot use this energy in any way, it is too disorganized. The measure of chaos in physics is called entropy. When useful energy deteriorates into heat, the amount of entropy increases, and the dissipated energy can no longer be used. The energy we can still use is called free energy. Whatever we do, we use it up, and that is why we need to produce energy all the time.

 

We discussed the pendulum as an example of a system where the energy goes from gravitational to kinetic and back to gravitational. The question was whether this motion can go forever. We decided to eliminate air by putting the pendulum under a dome and pumping out the gas to create a vacuum. Even this would not stop the pendulum from dissipating energy. In this case, the friction happened inside the string.

 

 

 

New usable energy can come from a number of sources, such as

• Sunlight. Solar panels convert it into electricity, and living plants convert it into chemical energy of carbohydrates; the Sun itself is powered by a nuclear reaction called fusion, in which atoms of helium and hydrogen collide and fuse together producing heavier atoms and tons of energy


• Fossil fuels (natural gas, coal, and oil). They have biological origin and therefore we can say they contain preserved accumulated sunlight


• Food. We burn it in our bodies so that we can move and think. Like fossils, this is also accumulated sunlight


• The energy of wind and water. It originates from the differences of the temperatures of different parts of Earth. Those differences exist because the Sun heats different parts of Earth differently. Thus, this is the Sun again


• Geothermal and seismic energy comes from the heat inside Earth, which is hot inside apparently due to a nuclear reaction. This reaction is different from the one that occurs inside the Sun. It is called fusion reaction when heavy atoms of uranium and other radioactive elements break into parts producing lighter atoms and lots of energy

 

 

Dan suggested that we use solar power and draw a sketch for his project. It included floating islands on the surface with solar panels on them connected to the colony by cables.

 

 

We also discussed the origin of the tides, lunar and solar, and considered them as a source of energy for our colony.

 

 

Importantly, we want to have our source of energy as ecologically friendly as possible. We discussed pollution caused by burning fossils, flooding and land deterioration caused by water power plants, large areas of land consumed by solar panels and windmills, and radioactive waste from nuclear power plants.

 

 

 

We decided to go with those new mini power reactors about the size of a hot tub that can work for 60 years without any service and produce enough energy to power a small town. The price is about $25 mln.

 

Hyperion Power Generation's nuclear reactor

Bill Gates about future of energy. Highly recommended.

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And then there was break.

 

 

 

 

HOMEWORK ASSIGNMENT:

 

In our next class, we will discuss some biological issues. All of us are now professional genetic engineers and we need to think about new creatures, plants and/or animals, that we can create combining genes from other animals/plants or just designing new genes. It would be nice if you can invent an animal or a plant that would be extremely useful for the colony, and give us a 3 to 5 min. presentation about your creature. Please be ready to tell us:

• what is the problem for which we need a solution
• how you address this problem with your invention
• describe the creature
• give us an idea of its design:
  • which animals/plants were your prototypes (if any) and gene sources
  • which genes you designed from scratch
  • which changes did applied after the birth (surgeries, implants, etc.) if at all

 It would also be great if you do some reading/research on the following topics:

• Genotype and phenotype
• Genes
• DNA and gene encoding
• Evolution by natural selection

As always, homework is optional but very much recommended.

Dear parents, I would highly encourage you to help you children with this assignment.

 

I look forward to seeing you all on Tuesday.

-Valéry

 

 

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