It has become a practice among many students (compared to a few decades back) to read only what is taught the day and not what happened before.
Though it is a good practice to start with current topic, revising back to the beginning as much as possible is very much helpful in performing well in exams. Every time you repeat, the mind seeks new meanings and interpretations and this becomes helpful while answering the HOTS questions (If you have the determination to answer every question to the best of your ability & beyond!) When we read again and again new questions related to the topic arises in our mind and the effort to answer the questions is the beginning of true learning. Only when you read with an active, curious and questioning mind, learning becomes effective.
And don’t rest until you find satisfying and convincing answers to your questions… The answers, the explanations and the logical reasoning developed by you will last forever. But always discuss those with a good teacher. Sometimes it happens that the explanations developed by oneself has some faulty considerations and may be violating the basic principles of conservation or some other of the sort.
I have used this idiomatic expressions which means being in friendly terms with both parties in a quarrel as the title of my post purposefully. A quarrel ensues when two parties find it difficult to reach a rapprochement over an issue concerning them .But the dismaying fact is that certain issues have inherent in them ,an enigmatic combination of thesis and antithesis. One such is the topic of the desirability of exams in Schools and Colleges.
Given the nature of this topic, I will hold an ambivalent approach to it. In other words,I will run with the Hare and hunt with the hounds. The teacher in me believes that exams are an integral part of teaching-learning process and exam should follow a certain amount of teaching- learning .The argument is that examinations are the tools , tailor -made for quantifying and evaluating the learning outcomes. Exam result provides the teacher with ample feedback on the academic status of the students .This feedback can subsequently used for the follow up.
The more liberal teacher in me holds a different standpoint. His voice is the echo of the agonized cry of a student who has become a beast academic burden and who struggles to keep pace with the curricular indoctrination that is done in distinct packages in every period .Things come out of the woodwork in each teaching period and an average student starts goofing up things .This pitiful child feels out of place. But Brutus is an honourable man.
There is no denying the fact that we can’t do away with examinations because there is no other effective alternative. Very often , absence of choices rule the roost. The only thing that we can do is to get our children better equipped for these exams that have become certitude in the life of a student so that he will feel relieved from the smothering exam syndromes.
Wishing tension -free exam days to the student fraternity.
Nicholas James is a motivational speaker from Australia. Born with phocomelia, a rare disorder characterised by the absence of legs and arms. As a child, he struggled mentally and emotionally as well as physically, but eventually came to terms with his disability. He presents motivational speeches worldwide which focus on living with disabilities and finding hope and meaning in life.
Vujicic asked his parents when he was aged 13 about his birth. Several days before he was born, there was no notification from a doctor or nurse that something was wrong. However, when he was born his mother asked a nurse how the baby was and there was a silence among the nurses. When his mother persisted and asked a doctor what had happened with the baby, he said “phocomelia”. As his mother worked as a paediatric nurse in charge of a delivery room, she immediately knew what the medical term meant. At first, she refused to see him or hold him when the nurse had him in front of her, but she and her husband tried to accept it and tried to understand God’s plan for their son through a strong faith in God
Even though his mother gave him a cushion to support himself, he overcame and taught himself how to stand up with a method by leaning his forehead over the wall and slowly standing up. Originally, he was born with combined two toes, so he could use them for rolling over, shoving and bracing himself. Because of this, his parents and doctor decided to have an operation to separate his toes so that he could use them as fingers to grab, turn pages and other functions. Even though the operation did not go as well as the doctor wanted, he tried to adapt using these freed toes and with the help of an electronic wheelchair, computer and mobile phone became more free.
After his mother showed him a newspaper article about a man dealing with a severe disability when he was seventeen, he started to give talks at his prayer group and later founded his non-profit organisation, Life Without Limbs.
He concludes that his childhood was an “amazingly normal childhood” and he advises readers to not give up, to change their circumstances if needed and to stop their concerns about whether their luck will be better and run after any desire.
Do you want to bring a big surprise to your teachers, parents and friends by scoring amazing marks in Physics exam?
Here are some tips!
Have you been branded as a slow learner or a weak students in Physics so far?
Do you fear of failure in Physics in the forthcoming examination?
Is Physics a nightmare to you?
Not any more !
Religiously follow these guidelines and you will be astonished by the results.
These are a set of instructions with proven track record
Caution!!!
These are not intended for students who score more than 90%, but for those students who score less than 40%. This will help the students to score more than 60 – 80% depending on how much you are able to follow the directions.
Following the guidelines will help you prepare yourselves to score more with a few days of hard work!
Einstein’s theory of relativity was beyond any doubt lovely, different from any other theory ever imagined by mankind. Newton described gravity merely as a force acting over a distance attracting any 2 masses, the force proportional to the product of the two masses and inversely proportional to the square of the distance between them. This simple straight forward theory worked well for over two hundred years.
Do you know there are a lot of Physics facts hidden behind a glass of beer.
Institute of Physics (UK) has launched a Christmas website based on beer, to help explain some of the more peculiar scientific phenomena hidden in a glass of beer.
http://www.physics.org/cheersphysics/
The site explains many facts of Physics too based on the beer story.
It says that the bubbles are not rising but they are constantly falling in a g;ass of beer. Can’t believe? Visit the site to know more.
The collection will also be helpful for students of other syllabuses.
The file consists of syllabus, key points, collection of very short Answer (1 mark), Short answer type question – solved (2 marks), short answers (3 marks), Long answers (5 marks), Solved numericals and 3 sample papers.
The contents are arranged chapter-wise. Any student will find this a boon for easy preparation and to score better marks in Physics.
We cannot imagine modern life without the car. The automobile has been one of the singular most amazing inventions of the 21st century and almost defines modern times. Inside of most mechanical petroleum based vehicles is the internal combustion engine.
Today we shall have a brief look at the internal combustion engine and it’s basic working principles.
Basically the the internal combustion engine is a cyclic machine that works on the basis of polytropic expansion laws.
polywhat?!
Ok so a polytropic process is one in which the gas equations work differently than that stated in boyle’s law because temperatures need to be constant for the famous law to work. (Pressure*Volume= constant at constant temperature)
Here since during expansion of the gases the temperature does not remain constant and hence the law looks like:
Pressure*Volumex =constant
The variable x depends upon the gas used.
So as you can see pressure will have to change greatly for the equivalent volume to change and to keep the equation valid. That’s exactly what happens in an internal combustion engine where an small explosion changes the pressure greatly but the limited volume is not much and hence the equivalent change in volume remains small.
First cycle: Suction
As you can see from the diagram the camshaft being slightly oval is rotating about a central point which for a certain time pushes the lever which opens the valve connecting the gasoline tank to the combustion chamber. The engine is so tuned such that when the fuel flows from the gasoline tank to the combustion chamber the bigger rotating structure downwards pulls the piston downwards. Hence the fuel gets trapped in the chamber when the valve closes.
Second cycle:Compression
This is the part where things get interesting. With the fuel trapped inside the chamber due to valve action the wheel rotates such that it pushes the piston above and compresses the fuel. This fuel now now has to withstand high pressure as the piston has lowered the volume greatly. When it is compressed at the maximum a spark plus in the chamber is ignited which causes a small explosion to increase pressure rapidly and push the piston downwards.[remember the part where i told you that the volume is quite limited but the change in pressure is enormous]
Third cycle: Expansion
Here work is obtained from the engine as it causes the rotation in the rotating part attached to the piston to increase. The expansion is the part where the actual energy is obtained from the engine. The wheel continues to rotate by inertia. This is why sometime you need to move the car a bit before getting it to work. It is because the first two parts of the cycle need energy to function and it’s the third cycle which actually provides work.
Fourth cycle: Exhaust
Now the second camshaft is made to rotate at such a speed that by the end of the third cycle the exhaust valve opens up and the fumes that remain after the explosion is forced out by the upward movement of the piston.
Now the second cycle starts where the piston is made to move by inertia and hence the cycle continues.
That’s it! That’s how the internal combustion engine works. Now obviously you will not get an exact replica of this engine inside your car. Rather they have as many as four piston moving up and down to form a 4-stroke internal combustion engine. Also they have a variety of cooling mechanisms and noise filters to reduce the noise from the explosion that takes place inside the machine. However this is the absolute basic and all other made upon this model. There are differences between a petrol and a diesel engine but then again they are not much different from this model.
So now the looking up the car engine won’t seem like an engineering job at NASA anymore, would it?!
As the world’s fossil fuels are continuously depleted with increasing use we run the risk of facing a shortage soon enough in the future. Alternatives are a must as we already face the heat here in India with capping of LPG cylinders. One of the biggest consumers of fossil fuels are petroleum-based vehicles. Whether it is a diesel car or a petrol car or a CNG vehicle it doesn’t really matter. They all use fossil fuels which are bound to run out one day or the other. We need to continuously improve current efficiencies of transportation vehicles while still improving on alternative energy sources. One of the biggest solutions to alternative energy solutions are using hydrogen instead of carbon based fuel as an energy source.
Hydrogen as a fuel has a lot of potential to be used as energy because it not only releases a large amount of energy when burnt but it also prevents the release of toxic fumes as pollutants.
Let’s do a little bit of math shall we?
I promise it won’t be too large.
Bond energies of hydrogen
The bond energy of the hydrogen bond is 103 kcal/mole. And the bond energy of the hydrogen oxygen bond is 110 kcal/mole. Also the oxygen molecule has 116 kcal/mole of energy.
Therefore the energy released on formation of the water molecule requires breaking one oxygen molecule and two hydrogen molecules first.
That would mean the energy required = 2 x 103 + 116 = 322 kcal/mole
But when water is formed the energy released is = 4 x 110 = 440 kcal/mole
Hence the net energy gain = 440 – 322 = 118 kcal/mole
And this simple math shows the huge amount of energy which is gained on burning hydrogen as a fuel. If a human being were to be powered up by a hydrogen engine he would run 52 miles on just 1 litre! Hydrogen based cars can theoretically provide mileage as good as 93 miles per gallon which is still much better than gasoline based cars providing 35 miles per gallon.
Yes and that’s exactly why hydrogen is a potential energy alternative.
This picture shows exactly what the components of the hydrogen economy consist of.I won’t talk about all the boring points in detail but only some of the parts which are really interesting.
Production and delivery
Hydrogen has a huge source in the form of our vast oceans and seas which provide an ample source of hydrogen. The problem is converting the water to hydrogen which requires energy in the first place.
Well right now they use natural gas and other petroleum products as well as biogas to produce hydrogen. Yes production is actually the biggest hurdle to the hydrogen economy. Hydrogen requires huge amounts of energy to be produced.(It only makes sense since it produces a huge amount of energy on combustion as well.) People are actively working on getting hydrogen to be obtained from a safe source. There are many technologies like aluminium based production (still waiting to be patented) for effective hydrogen production.
And yes there are several hoaxes doing the rounds around the internet which claim to have made super efficient methods to obtain hydrogen from water and hence make cars that run miles on just plain water!!! Well NASA itself has yet to make such a breakthrough but of course there is no giving up hope as people are still trying.
Although I am optimistic that this can be effectively taken care of using solar , wind , hydel power and various other renewable energy sources(like i told you before the future depends on all energy renewables working together) Then the hydrogen can be transported using storage tanks to fuel stations where the vehicles can refill their tanks!
And no I am not talking about science fiction. This is reality as industries work to implement these systems into the current economy.
Fuel cells
This is the talk of the town when it comes to hydrogen based economy. Fuel cells use a continuous supply of hydrogen to be directly converted to energy using a chemical reaction. This means efficiencies are quite high when using a fuel cell to power up a vehicle as compared to using internal combustion engines to power up a car.
There is huge money in the R&D for fuel cells in the automobile sector.There have been lots of hydrogen based fuel cells which are running commercially as well. Although there has been electric vehicles which have been shown to have much higher efficiencies they lack the power or speed pick up of fuel cell based cars and car maniacs out there swear by top speeds and revving pick up.
Storage
Now this is a real tricky issue hydrogen is the lightest of all elements out there and it is easily the least dense of all gases. In fact 1 gram of hydrogen would occupy as much as 22.4 litres! that too at 0 degrees celsius. Not too good when considering that we would need more than that to provide decent mileage to the vehicles. Well scientists have been looking for ways to combat this dilemma.
One of the ways include in-situ production of hydrogen.
It means the hydrogen would not be carried directly as a fuel. Instead hydrogen containing compounds would be used to generate the hydrogen at the time of running the car. However this method reduces efficiency significantly and renders the use of the vehicle as useless!
Another one of the methods include storage of hydrogen in a really efficient way
This means nanotechnology again! Yes the use of carbon nanotubes to store hydrogen has been deemed a potentially powerful method to store huge quantities of hydrogen in the vehicles. That however is a costly method and current research includes making hydrogen storage even cheaper.
Safety?
Now this is a bit of a tricky issue because hydrogen is even more susceptible to combustion than petroleum. Although that also means that fires breaking out won’t produce toxic fumes but then again they will bring out a bigger bang if they accidentally catch fire. Also current hydrogen storage techniques are not exactly 100% leak proof which means the dangers of accidents are higher! However this can be offset by using standards and protocols to enhance the safety factor of using hydrogen.
So what’s the real problem in implementation of hydrogen as a potential energy source?
Well this again lies in costs. Changing equipment and technology that has been built on petroleum will cost huge amounts and also current petroleum-based vehicles and fuel rates are cheaper than those of hydrogen based ones. Of course this should rapidly change in the very close future. In fact there are many companies already that provide hydrogen cars and hydrogen refuelling outlets.
Yes these are real hydrogen cars in the market out there.
Ocean energy
Now renewable energy sources come in various forms and make great pollution alternatives to coal and other exhaustive resources. Now scientists have been looking for all sorts of alternatives and creativity is often more valued than analytical solutions. Our great oceans store vast amounts of energy in the form of heat(anyone remember that water has the highest specific heat capacity?) mechanical (think thousands of gallons of moving water and the momentum it possesses!) as well as chemical energy (water has a lot of energy in those bonds between hydrogen and oxygen).
Some forms of utilizing tidal energy
1) Wave energy
Here the moving energy of waves is utilized. As can be seen from the figure the moving energy of the waves forces air out of the turbine when it is moving up and forcing air into the turbine when it is moving down. Hence this movement of air can be used to turn turbines . It creates a small source of power but nevertheless it is used in coastal areas for powering small lighthouses and other small electrical equipment.
Sometimes the motion of the wave itself can be used to power a piston to move up and down which in turn can turn a generator.
2)Tidal Energy
Tidal energy is the real current practical source of energy. It uses the tides to store water during high tide and then during low tide the water is released just like a hydroelectric power dam. It’s really simple but the problem is that the tides need to rise really high in order to make it work effectively.
However India’s own coastal lines are quite suitable for this sort of energy and some our IITs are working on making tidal energy a viable source of energy to provide the coastal needs of power.
3) Ocean thermal energy
There is a vast difference in the temperatures of the surface of the ocean and the bottom of the ocean. This temperature difference itself can be used to produce electricity.
Now normally one would assume this electricity produced to be of very poor voltage.(In the seebeck effect about 500 degrees celsius produces about 500 mV).
Hence it has not gained much popularity as an alternative energy source.
New research
Now don’t be so quick to cutting out Ocean Thermal Energy Conversion(OTEC). Ocean thermal energy can be used to generate electricity in new ways it seems again thanks to the potential boundless limits of nanotechnology. It seems scientists have found new ways to harness the heat to generate electricity.
Over time if this new technology could be developed to harness the temperature difference between the surface of the ocean and it’s bottom there could be potentially boundless limits since it could also use the temperatures found in factories, automobiles, deserts(think of deserts as giant energy batteries or so that’s what i think.)
Another interesting phenomenon about tidal energy is that it is not a solar based energy source(most of our energy sources are solar based directly or indirectly) but it is actually based on the lunar force of attraction. So it seems that using the moon as a potential energy source is by itself quite an innovative idea…don’t you think?
