Science

Hey fellow science fans, tell us interesting facts for fun!

Ribosomes are the way to create proteins, and are also made of proteins. They are also necessary for life in all known organisms.

So, fellow science fans, how did they come to be?



For a more random fact, octopuses brains have 40 different lobes and their arms also have the ability to "think" to a certain degree.

The crankshaft stroke in a reciprocating engine can have a very significant effect on overall performance. As the stroke increases, the connecting rod is forced to travel at a faster speed in relation to engine RPM. That is to say, a connecting rod connecting to a crankshaft with a 4" stroke at 3,000 RPM will travel faster than the same length connecting rod connected to a 3" stroke crankshaft at the same RPM.

To illustrate this, take a ratchet (scenario 1), place your finger (point A) near the head (point B) and spin it around. Notice how quickly point A completes 360 degrees of rotation. Now (scenario 2), place your finger (point A) near the end of the handle and spin it around. Notice how long it takes to complete 360 degrees of rotation. The only way to for scenario 2 complete 360 degrees of rotation in the same time scenario 1 is to spin the ratchet at a much faster speed due to the fact that point A has to cover a much larger circumference. In a reciprocating engine, assuming the same RPM, a connecting rod attached to a longer stroke crankshaft will have to travel a much larger circle and therefore travel much faster than a connecting rod attached to a shorter stroke crankshaft.

So, what effect does this have on performance? Since the piston is attached to the connecting rod, the reciprocating speed of the connecting rod directly determines the reciprocating speed of the piston. The faster the piston travels, the more "void" is opened up across X time during the intake phase (piston travels downwards). The larger the "void," the more volume is required to fill it. The faster a "void" can be opened up, the stronger the pressure differential can become. In the case of a fast-moving piston, the intake charge will "chase" the piston resulting in a slower "balancing" of pressure. This allows a larger volume of air to be drawn into the cylinder, due to longer-sustained pressure differential, and combined with proper fueling, will result in more power.

In contrast, a slower-moving piston causes the intake charge to "catch" the piston which results in turbulence within the cylinder. This has pro/con effect. On the plus side, the turbulation causes improved aeration of the fuel which results in improved efficiency and emissions. However, this turbulence also causes pressure differentiation to equalize much sooner, resulting in less air to be drawn into the cylinder and thus limits power potential.

Very generally speaking, faster piston velocity produces more peak power while slower piston velocity yields better efficiency. This does not take into account intake manifold/cylinder head design, fueling style (fuel injection vs carburetor), camshaft, cylinder bore, number of valves, exhaust configuration and RPM limiting due to bearing stress (this is a biggie). There are many, many factors that determine the overall performance of a given internal combustion engine.

traps are gay

The Hubble Space Telescope weighs 12 tons (10,896 kilograms), is 43 feet (13.1 meters) long, and cost $2.1 billion to originally build!

Adult cells have the genetic material that is the basis for every other cell. Irreversible inactivation is a lie :)

Methionine is not the only start code for proteins, despite popular belief. There are many prokaryotic species with lucine and valine start codes.

What are two things all straight-piped trucks have in common? One, they're obnoxiously loud. Two, they're throwing away as much power as they're gaining.

Exhaust backpressure. Everyone looking for cheap and easy power wants to be rid of it but there are a few critical details that very few people even know of. A large one, and one which can actually cost you power if tampered with inappropriately, is exhaust port pressure in the cylinder head.

During the exhaust stroke in a four-cycle internal combustion reciprocating engine, the exhaust valve in the cylinder head opens, allowing spent, combusted fuel/air mixture to exit the cylinder through the exhaust system. This exhaust is forced through the system as a result of the piston traveling upwards, decreasing cylinder volume and increasing pressure, causing the exhaust to push towards the relatively low-pressure exhaust system. As a result of valve timing, near the end of the exhaust cycle, the intake valve begins to open while the exhaust valve is still closing. This critical phase is known as "overlap."

Overlap is the range of degrees of camshaft rotation in which the intake and exhaust valves are open at the same time. The "length" of this overlap is a product of camshaft duration and lobe separation angle (LSA). In regards to OEM camshafts, these dimensions vary hugely. A standard passenger car will use a different camshaft profile as a truck which will use a different cam profile as a sports car. As such, the effects of manipulating exhaust backpressure will have varying effects depending on application. Because of this, it is virutally impossible to generalize the results of modifying exhaust characteristics across multiple demographics. However, the "base" effects of increasing or decreasing exhaust backpressure, in regards to exhaust port pressure can be determined.

During the exhaust phase, the "head" of the exhaust pulse pushes static, atmospheric air away towards the tailpipe and outside of the vehicle. As a result of this purging, a temporary, low-pressure void is left behind the pulse in the exhaust system which helps draw subsequent exhaust pulses from the cylinder. During the overlap phase, the intake valve opens while the exhaust valve is still closing. This creates two paths which the intake charge can take: following the piston or flowing through the exhaust port. Obviously, one wants the intake charge to follow the piston and not escape through the exhaust. Fortunately, despite the reduced pressure at the exhaust port as a result of the previous cycle's traveling pulse, the majority of the intake charge will "chase" the piston due to the much lower pressure in the cylinder as a result of expansion. However, as the intake charge fills the cylinder, pressure begins to rise, equalizes with and then surpasses the pressure at the exhaust port. As a result, a portion of the mixture will move towards the lower pressure at the exhaust port and slip through the exhaust rather than remain inside the cylinder. As a result, this results in less fuel/air mixture inside the cylinder which ultimately results in less power during the combustion phase.

So, how does exhaust backpressure affect things? Simply put, any kind of pressure in the exhaust system, especially at the manifold(s), creates resistance to the flow of exhaust, which creates an increase in system pressure which "stacks" at the exhaust port. The more restrictive the exhaust is, the higher the pressure at the exhaust port. The higher the pressure at the exhaust port, the longer it takes for cylinder pressure to surpass port pressure and as a result, less fuel/air mixture is lost through the exhaust before the valve completely closes. Conversely, if exhaust backpressure is reduced, port pressure will also be reduced and as a result, the rising cylinder pressure will surpass the port pressure sooner, resulting in the intake charge pushing towards the port sooner and result in a greater loss which results in less power potential during combustion.

Taking things a bit further, it is important to note that in a low-pressure exhaust system, although a larger portion of the intake charge will escape the cylinder, costing power, the low pressure of such a system also reduces pumping losses during the exhaust cycle as less pressure is placed upon the piston while it drives out the exhaust. This will increase power and can even extend bearing life. Conversely, a higher-pressure system retains more fuel/air mixture which increases power potential, however, higher pressure is placed upon the piston during the exhaust cylce, costing power. Also, such a system may draw some of the escaping exhaust back into the cylider. Although this will "water down" the fuel/air mixture, the inert exhaust can help stabilize the mixture which can be critical in engines that generate large amounts of cylinder pressure during compression.

What is the optimal amount of exhaust backpressure? The short answer is that it depends entirely on application. Many exhaust systems from the factory are specifically designed to reduce noise and tend to generate excessive amounts of backpressure. Replacing the manifolds with headers of appropriate runner size and swapping the muffler with a high-flow design are generally guaranteed ways of increasing engine power across it's RPM range without causing excessive swings of it's powerband. Increasing and/or decreasing pipe diameter across the system and switching from a single pipe to two pipes and vice versa can significantly shift an engine's powerband but it is important to remember that, especially when little to no modifications are made to engine induction, the loss in one area can be significantly greater than the increase in another.

As always, there are many, many factors that determine engine performance, including the characteristics of the vehicle itself.

that is experience, not science

Eratosthenes was the first in 240BC to not only theoritize that the earth was round, but also calculate its circumference with a surprising degree of accuracy. His only help was the sun, a stick, and mathematics.

In order to create the Pythagorean theorem the Greeks borrowed heavily from the ancient Egyptians who had been using similar math for hundreds of years(though hadn't developed a universal theorem).

If a rabbit does not eat, it will go into gastrointestinal stasis. This means its gastrointestinal system stops working - it cannot eat, it cannot digest food, it cannot poop.

People are often surprised at how easily rabbits get sick. Rabbits didnt evolve to survive very long, they just evolved to make lots of babies. Also, pet rabbits are different to wild rabbits, and most pet bunnies wouldnt last a day in the wild.

Sorry for the lack of apostrophes. They wont show up for some reason.

We dont have the technology to go back to the moon

[image: i38.photobucket.com]

BHAHAHA