Category: A-Level Physics

Space Revision

If you wish to do a bit of revision or learning on KS3, 4 or 5 space. Then try some of the resources here, you can have a PPT or PDF.

Feel free to use for school use, but all images are copyright so no profit or derivatives which you sell!

 

Animated Science Space Revision (PDF)

Animated Science Space Revision (PPTX)

Permanent link to this article: https://animatedscience.co.uk/2017/space-revision

Turbo Chargers – Amazing

Turbo gives petrol cars a boost as diesel faces backlash – http://www.bbc.co.uk/news/business-34731463

 

Turbo gives petrol cars a boost as diesel faces backlash

Graphic of Kia Proceed car

Looking at Kia’s new Proceed T-GDi GT-Line, with its sporty looks and handling, you might expect a big, thirsty engine under the bonnet.

Instead, it has a frugal three-cylinder 1.0 litre petrol engine that can still deliver 0-62mph (0-100km/h) in 10.7 seconds, nearly 60 miles to the gallon, and CO2 emissions of 115g/km.

A few years ago, this kind of performance would’ve been considered outstanding.

Thanks to turbo tech, these traditionally-fuelled internal combustion engines are now offering better fuel economy and lower emissions, without comparable loss of performance.

And in light of the recent Volkswagen diesel emissions scandal – and tighter emissions regulations worldwide – company car fleet directors are taking note.

VW logo on rusty Beetle

“Diesel has emerged as the dominant fuel type for company cars, as a result of great fuel efficiency, performance and low cost of ownership under the government’s CO2 emissions based tax regime,” says Gerry Keaney, chief executive of the British Vehicle Rentals and Leasing Association, whose members own or fleet manage more than three million cars in the UK.

“But the diesel proportion of new registrations has been falling gradually for some time, as modern petrol powered cars have become better at delivering similar benefits, and we expect this trend to gather pace.”

In the UK, even company car buyers now see downsized petrol engines, many emitting around 100g/km CO2, as a viable, efficient alternative to diesel.

Old-fashioned car

This is not just down to “anti-diesel sentiment”, says Al Bedwell, director, global powertrains at LMC Automotive. “It has more to do with petrol getting better and staging a fight-back, especially in small cars in Western Europe.”

Manufacturers such as Ford, Opel/Vauxhall, Hyundai and Volkswagen are all offering similarly downsized petrol engines these days, many emitting around 100g/km of CO2.

In Europe, diesel’s share of the market is set to drop from 53.3% of the market in 2014 to 51.5% in 2015, says Mr Bedwell, then continue sliding to 35% by 2020.

Power boost

Turbo chargers are traditionally associated with diesel engines, which needed a boost to give them more oomph. They weren’t “much fun to drive” without them, says Guillaume Devauchelle, head of innovation and science at automotive technology company, Valeo.

And the relative cost of adding turbo to an expensive diesel engine was lower, he explains.

Light vehicles market graphicImage copyrightGetty Images

But turbos are now increasingly infiltrating petrol engines because they deliver dramatic emissions reductions and improvements in fuel economy, without sacrificing performance, says Craig Balis, chief technology officer of Honeywell Transportation Systems, the world’s largest turbo maker.

A two-litre turbo-charged four cylinder petrol engine can match the output of a three-litre naturally aspirated V6 petrol engine, he says, so “the technology we have is really a no-compromise solution”.

Turbos work by using the engine’s exhaust gas to drive a turbine, which in turn drives a compressor, which compresses air. This air is then forced into the combustion chamber where it mixes with fuel to create additional power.

This means the engine won’t have to burn so much fuel to deliver the same output.

Video grab of smaller v, larger engine

“Our turbos for passenger vehicles have turbines that spin at 200,000-300,000 revolutions per minute (rpm), generating temperatures of up to 1,000 degrees Celsius, so the metal is literally glowing red,” Mr Balis says.

By comparison petrol engines operate at just 6,000-7,000 rpm and diesel at 5,000-6,000rpm.

To cope with such extreme speed, pressure and heat, turbos need to be incredibly robust, so Honeywell is using ball bearings and other technologies that have been developed for military aircraft by the company’s aerospace division.

The turbos are also coupled with intercoolers that cool the airflow and increases its density as it is supplied to the engine, and with oil cooling systems that prevent overheating.

Instant power

Turbos are often combined with direct or indirect fuel injectors and variable valve lift or timing systems to make the process even more efficient.

Electrified superchargers, which compress air for just a few hundred milliseconds to add brief low-end torque until the turbo charger kicks in, will also hit the market in the next few months.

Over the next five years, we’ll go from about a third to around half the cars sold having turbo chargers, and the growth will continue. We call this the ‘golden age of turbo’

Terrence Hahn, Honeywell TS

E-chargers, or e-turbos, will transform the driving experience, believes Mr Devauchelle, as they eliminate what’s called turbo lag – that slight delay in power boost you experience after pressing the accelerator.

“The turbo increases the engine’s maximum power. The e-charger gets you there even quicker,” he explains.

As such, e-turbos may rival established twin-turbo technology, where a small turbo takes care of the early stages of acceleration before the second turbo takes over.

The e-turbos’ batteries can be recharged in different ways, for instance by capturing energy during braking, explains Mr Hahn.

With enough electric power, e-chargers could take over more and more of the work done by the turbo.

Tesla electric car

Eventually carmakers will redesign vehicle architecture, moving from standard 12-volt batteries to higher voltage systems.

Forty-eight volt architecture is emerging in luxury cars with many electric components, but e-chargers can also run on 12-volt batteries if they are only required to deliver brief boosts, explains Mr Devauchelle.

‘Golden age of turbo’

“Petrol power is moving from naturally aspirated engines to turbo charged engines at a faster rate than ever before,” says Terrence Hahn, president and chief executive of Honeywell Transportation Systems.

“Over the next five years, we’ll go from about a third to around half the cars sold having turbo chargers, and the growth will continue,” he predicts.

“We call this ‘the golden age of turbo’.”

But there is no silver bullet as carmakers continue to grapple with ever-stricter emissions regulation, coupled with huge penalties for non-compliance.

Any number of combinations of e-chargers, turbo chargers, multi-stage boosting, fuel injection, variable valve systems, and combustion-electric hybrid technologies are being explored.

“During 30 years in the industry, I have never before seen so much diversity,” says Mr Devauchelle.

“Nobody can afford the penalties.”

Permanent link to this article: https://animatedscience.co.uk/2015/turbo-chargers-amazing

What is Newton’s second law of motion?

What is Newton’s second law of motion?

http://gu.com/p/3zpeb

This is a really good post to help you find out!

Permanent link to this article: https://animatedscience.co.uk/2014/what-is-newtons-second-law-of-motion

Can flywheel technology drive out the battery from car hybrids? | Corrinne Burns

Can flywheel technology drive out the battery from car hybrids? | Corrinne Burns

http://gu.com/p/3m6ng

Permanent link to this article: https://animatedscience.co.uk/2014/can-flywheel-technology-drive-out-the-battery-from-car-hybrids-corrinne-burns

Black hole to ‘eat biggest meal’

Black hole to ‘eat biggest meal’ http://www.bbc.co.uk/news/world-middle-east-25678737

Permanent link to this article: https://animatedscience.co.uk/2014/black-hole-to-eat-biggest-meal

What is the second law of thermodynamics?

What is the second law of thermodynamics?

http://gu.com/p/3kt6q  from The Observer

Thermodynamics is the study of heat and energy. At its heart are laws that describe how energy moves around within a system, whether an atom, a hurricane or a black hole. The first law describes how energy cannot be created or destroyed, merely transformed from one kind to another. The second law, however, is probably better known and even more profound because it describes the limits of what the universe can do. This law is about inefficiency, degeneration and decay. It tells us all we do is inherently wasteful and that there are irreversible processes in the universe. It gives us an arrow for time and tells us that our universe has a inescapably bleak, desolate fate.

Despite these somewhat deflating ideas, the ideas of thermodynamics were formulated in a time of great technological optimism – the Industrial Revolution. In the mid-19th century, physicists and engineers were building steam engines to mechanise work and transport and were trying to work out how to make them more powerful and efficient.

Many scientists and engineers – including Rudolf Clausius, James Joule and Lord Kelvin – contributed to the development of thermodynamics, but the father of the discipline was the French physicist Sadi Carnot. In 1824 he published Reflections on the Motive Power of Fire, which laid down the basic principles, gleaned from observations of how energy moved around engines and how wasted heat and useful work were related.

The second law can be expressed in several ways, the simplest being that heat will naturally flow from a hotter to a colder body. At its heart is a property of thermodynamic systems called entropy – in the equations above it is represented by “S” – in loose terms, a measure of the amount of disorder within a system. This can be represented in many ways, for example in the arrangement of the molecules – water molecules in an ice cube are more ordered than the same molecules after they have been heated into a gas. Whereas the water molecules were in a well-defined lattice in the ice cube, they float unpredictably in the gas. The entropy of the ice cube is, therefore, lower than that of the gas. Similarly, the entropy of a plate is higher when it is in pieces on the floor compared with when it is in one piece in the sink.

A more formal definition for entropy as heat moves around a system is given in the first of the equations. The infinitesimal change in entropy of a system (dS) is calculated by measuring how much heat has entered a closed system (δQ) divided by the common temperature (T) at the point where the heat transfer took place.

The second equation is a way to express the second law of thermodynamics in terms of entropy. The formula says that the entropy of an isolated natural system will always tend to stay the same or increase – in other words, the energy in the universe is gradually moving towards disorder. Our original statement of the second law emerges from this equation: heat cannot spontaneously flow from a cold object (low entropy) to a hot object (high entropy) in a closed system because it would violate the equation. (Refrigerators seemingly break this rule since they can freeze things to much lower temperatures than the air around them. But they don’t violate the second law because they are not isolated systems, requiring a continual input of electrical energy to pump heat out of their interior. The fridge heats up the room around it and, if unplugged, would naturally return to thermal equilibrium with the room.)

This formula also imposes a direction on to time; whereas every other physical law we know of would work the same whether time was going forwards or backwards, this is not true for the second law of thermodynamics. However long you leave it, a boiling pan of water is unlikely to ever become a block of ice. A smashed plate could never reassemble itself, as this would reduce the entropy of the system in defiance of the second law of thermodynamics. Some processes, Carnot observed, are irreversible.

Carnot examined steam engines, which work by burning fuel to heat up a cylinder containing steam, which expands and pushes on a piston to then do something useful. The portion of the fuel’s energy that is extracted and made to do something useful is called work, while the remainder is the wasted (and disordered) energy we call heat. Carnot showed that you could predict the theoretical maximum efficiency of a steam engine by measuring the difference in temperatures of the steam inside the cylinder and that of the air around it, known in thermodynamic terms as the hot and cold reservoirs of a system respectively.

Heat engines work because heat naturally flows from hot to cold places. If there was no cold reservoir towards which it could move there would be no heat flow and the engine would not work. Because the cold reservoir is always above absolute zero, no heat engine can be 100% efficient.

The best-designed engines, therefore, heat up steam (or other gas) to the highest possible temperature then release the exhaust at the lowest possible temperature. The most modern steam engines can get to around 60% efficiency and diesel engines in cars can get to around 50% efficient. Petrol-based internal combustion engines are much more wasteful of their fuel’s energy.

The inefficiencies are built into any system using energy and can be described thermodynamically. This wasted energy means that the overall disorder of the universe – its entropy – will increase over time but at some point reach a maximum. At this moment in some unimaginably distant future, the energy in the universe will be evenly distributed and so, for all macroscopic purposes, will be useless. Cosmologists call this the “heat death” of the universe, an inevitable consequence of the unstoppable march of entropy.

Permanent link to this article: https://animatedscience.co.uk/2013/what-is-the-second-law-of-thermodynamics

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