HORSEPOWER - 1 horsepower is equivalent to 746 watts. So if you took a 1-horsepower horse and put it on a treadmill, it could operate a generator producing a continuous 746 watts. One of the areas where people talk most about horsepower is in the area of high-performance cars. A car is considered to be "high performance" if it has a lot of power relative to the weight of the car. This makes sense -- the more weight you have, the more power it takes to accelerate it. For a given amount of power you want to minimize the weight in order to maximize the acceleration.

The 1974 Dodge Charger that Richard Petty drove to his fifth and sixth Grand National/Winston Cup Series Championship in 1974 and 1975 and was used for his victory at the 1974 Daytona 500. The 2018 Dodge Charger SRT 392 cranks out 485 horsepower and 475 pound-feet of torque, says the automaker. 

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Horsepower

How Horsepower Works

BY MARSHALL BRAIN

Chances are you've heard about horsepower.

Just about every car ad on TV mentions it, people talking about their cars bandy the word about and even most lawn mowers have a big sticker on them to tell you the horsepower rating.

But what is horsepower, and what does the horsepower rating mean in terms of performance? In this article, you'll learn exactly what horsepower is and how you can apply it to your everyday life.

The term horsepower was invented by the engineer James Watt.

Watt lived from 1736 to 1819 and is most famous for his work on improving the performance of steam engines.

We are also reminded of him every day when we talk about 60-watt light bulbs.

The story goes that Watt was working with ponies lifting coal at a coal mine, and he wanted a way to talk about the power available from one of these animals.

He found that, on average, a mine pony could do 22,000 foot-pounds of work in a minute.

He then increased that number by 50 percent and pegged the measurement of horsepower at 33,000 foot-pounds of work in one minute.

It is that arbitrary unit of measure that has made its way down through the centuries and now appears on your car, your lawn mower, your chain saw and even in some cases your vacuum cleaner.

What horsepower means is this: In Watt's judgement, one horse can do 33,000 foot-pounds of work every minute.

So, imagine a horse raising coal out of a coal mine as shown above.

A horse exerting 1 horsepower can raise 330 pounds of coal 100 feet in a minute, or 33 pounds of coal 1,000 feet in one minute, or 1,000 pounds 33 feet in one minute.

You can make up whatever combination of feet and pounds you like.

As long as the product is 33,000 foot-pounds in one minute, you have a horsepower.

Y­ou can probably imagine that you would not want to load 33,000 pounds of coal in the bucket and ask the horse to move it 1 foot in a minute because the horse couldn't budge that big a load.

You can probably also imagine that you would not want to put 1 pound of coal in the bucket and ask the horse to run 33,000 feet in one minute, since that translates into 375 miles per hour and horses can't run that fast.

However, if you have read How a Block and Tackle Works, you know that with a block and tackle you can easily trade perceived weight for distance using an arrangement of pulleys.

So you could create a block and tackle system that puts a comfortable amount of weight on the horse at a comfortable speed no matter how much weight is actually in the bucket.

Horsepower can be converted into other units as well. For example:

·  1 horsepower is equivalent to 746 watts. So if you took a 1-horsepower horse and put it on a treadmill, it could operate a generator producing a continuous 746 watts.

·  1 horsepower (over the course of an hour) is equivalent to 2,545 BTU (British thermal units). If you took that 746 watts and ran it through an electric heater for an hour, it would produce 2,545 BTU (where a BTU is the amount of energy needed to raise the temperature of 1 pound of water 1 degree F).

·  One BTU is equal to 1,055 joules, or 252 gram-calories or 0.252 food Calories. Presumably, a horse producing 1 horsepower would burn 641 Calories in one hour if it were 100-percent efficient.

In this article, you'll learn all about horsepower and what it means in reference to machines.

Measuring Horsepower

If you want to know the horsepower of an engine, you hook the engine up to a dynamometer.

A dynamometer places a load on the engine and measures the amount of power that the engine can produce against the load.

Similarly, if you attach a shaft to an engine, the engine can apply torque to the shaft.

A dynamometer measures this torque. You can easily convert torque to horsepower by multiplying torque by rpm/5,252.

You can get an idea of how a dynamometer works in the following way: Imagine that you turn on a car engine, put it in neutral and floor it.

The engine would run so fast it would explode. That's no good, so on a dynamometer you apply a load to the floored engine and measure the load the engine can handle at different engine speeds.

You might hook an engine to a dynamometer, floor it and use the dynamometer to apply enough of a load to the engine to keep it at, say, 7,000 rpm.

You record how much load the engine can handle. Then you apply additional load to knock the engine speed down to 6,500 rpm and record the load there.

Then you apply additional load to get it down to 6,000 rpm, and so on.

You can do the same thing starting down at 500 or 1,000 rpm and working your way up.

What dynamometers actually measure is torque (in pound-feet), and to convert torque to horsepower you simply multiply torque by rpm/5,252.

Graphing Horsepower

If you plot the horsepower versus the rpm values for the engine, what you end up with is a horsepower curve for the engine.

A typical horsepower curve for a high-performance engine might look like this (this happens to be the curve for the 300-horsepower engine in the Mitsubishi 3000 twin-turbo):

Measuring horsepower requires a power-reading dynamometer. Learn how plotting horsepower against rpm values produces a graph called a horsepower curve.

What a graph like this points out is that any engine has a peak horsepower -- an rpm value at which the power available from the engine is at its maximum.

An engine also has a peak torque at a specific rpm.

You will often see this expressed in a brochure or a review in a magazine as "320 HP @ 6500 rpm, 290 lb-ft torque @ 5000 rpm" (the figures for the 1999 Shelby Series 1).

When people say an engine has "lots of low-end torque," what they mean is that the peak torque occurs at a fairly low rpm value, like 2,000 or 3,000 rpm.

Another thing you can see from a car's horsepower curve is the place where the engine has maximum power.

When you are trying to accelerate quickly, you want to try to keep the engine close to its maximum horsepower point on the curve.

That is why you often downshift to accelerate -- by downshifting, you increase engine rpm, which typically moves you closer to the peak horsepower point on the curve.

If you want to "launch" your car from a traffic light, you would typically rev the engine to get the engine right at its peak horsepower rpm and then release the clutch to dump maximum power to the tires.

One of the areas where people talk most about horsepower is in the area of high-performance cars. In the next section, we'll talk about the connection there.

TORQUE

Imagine that you have a big socket wrench with a 2-foot-long handle on it, and you apply 50 pounds of force to that 2-foot handle.

What you are doing is applying a torque, or turning force, of 100 pound-feet (50 pounds to a 2-foot-long handle) to the bolt.

You could get the same 100 pound-feet of torque by applying 1 pound of force to the end of a 100-foot handle or 100 pounds of force to a 1-foot handle.

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Horsepower in High-performance Cars

A car is considered to be "high performance" if it has a lot of power relative to the weight of the car.

This makes sense -- the more weight you have, the more power it takes to accelerate it.

For a given amount of power you want to minimize the weight in order to maximize the acceleration.

The following table shows you the horsepower and weight for several high-performance cars (and one low-performance car for comparison). 

In the chart you can see the peak horsepower, the weight of the car, the power-to-weight ratio (horsepower divided by the weight), the number of seconds the car takes to accelerate from zero to 60 mph, and the price.

You can see a very definite correlation between the power-to-weight ratio and the 0-to-60 time -- in most cases, a higher ratio indicates a quicker car. Interestingly, there is less of a correlation between speed and price. The Viper actually looks like a pretty good value on this particular table!

If you want a fast car, you want a good power-to-weight ratio. You want lots of power and minimal weight.

So the first place to start is by cleaning out your trunk.

Marshall Brain, Founder 
Marshall Brain is the founder of HowStuffWorks. He holds a bachelor's degree in electrical engineering from Rensselaer Polytechnic Institute and a master's degree in computer science from North Carolina State University. Before founding HowStuffWorks, Marshall taught in the computer science department at NCSU and ran a software training and consulting company. Learn more at his site.

https://auto.howstuffworks.com/horsepower.htm

 

ION EXCHANGE AND MEMBRANE PROCESSES - Ion exchange is primarily used for the removal of hardness ions, such as magnesium and calcium, and for water demineralization. Reverse osmosis (RO) and electrodialysis, both membrane processes, remove dissolved solids from water using membranes. Ion exchange units can be used to remove any charged (ionic) substance from water, but are usually used to remove hardness and nitrate from groundwater. Water is pretreated to reduce the suspended solids and total dissolved solids (TDS) load to the ion-exchange unit. Ion exchange effectively removes more than 90 percent of barium, cadmium, chromium (111), silver, radium, nitrites, selenium, arsenic (V), chromium (VI), and nitrate. Ion exchange is usually the best choice for small systems that need to remove radionuclides.

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Ion Exchange and Membrane Processes

The ABC's of Ion Exchange and  Demineralization

Ion exchange and membrane processes are becoming used extensively in water and wastewater treatment.

Ion exchange is primarily used for the removal of hardness ions, such as magnesium and calcium, and for water demineralization.

Reverse osmosis (RO) and electrodialysis, both membrane processes, remove dissolved solids from water using membranes.

Ion exchange units can be used to remove any charged (ionic) substance from water, but are usually used to remove hardness and nitrate from groundwater.

Water is pretreated to reduce the suspended solids and total dissolved solids (TDS) load to the ion-exchange unit.

Methods of pretreatment include:

·   filtration,

·   coagulation and filtration,

·   cold lime with or without soda ash,

·   hot lime with or without soda ash,

·   evaporation or distillation,

·   electrodialysis,

·   RO,

·   continuous deionization,

·   ultrafiltration,

·   degasification, or

·   combinations of the above. (Source: Owens, 1995)

RO systems are compact, simple to operate, and require minimal labor, making them suitable for small systems. They are also suitable for systems where there is a high degree of seasonal fluctuation in water demand.

Electrodialysis is a process that also uses membranes. However, in electrodialysis, direct electrical current is used to attract ions to one side of the treatment chamber. Electrodialysis systems include a source of pressurized water, a direct current power supply, and a pair of selective membranes.

The Ion Exchange Process

Ion exchange effectively removes more than 90 percent of barium, cadmium, chromium (111), silver, radium, nitrites, selenium, arsenic (V), chromium (VI), and nitrate. Ion exchange is usually the best choice for small systems that need to remove radionuclides.

Advantages
Ion exchange process, like reverse osmosis, can be used with fluctuating flow rates.

·   Effluent contamination is virtually impossible.

·   Large variety of specific resins are available from suppliers. Each resin is effective in removing specific contaminants.

Limitations
Ion exchange waste is highly concentrated and requires careful disposal.

·   Potential for unacceptable levels (peaks) of contamination in effluent.

·   Usually not feasible with high levels of TDS.

·   Pretreatment required for most surface waters.

·   Ion exchange units also are sensitive to the presence of competing ions. For example, influent with high levels of hardness will compete with other cations (positive ions) for space on the exchange medium, and the exchange medium must be regenerated more frequently.

Process
Inorganics removal is accomplished through adsorption of contaminant ions onto a resin exchange medium.

As the name implies, one ion is substituted for another on the charged surface of the medium, which is usually a synthetic plastic resin.

This resin surface is designed as either cationic or anionic (negatively charged). The exchange medium is saturated with the exchangeable ion before treatment operations.

During ion exchange, the contaminant ions replace the regenerant ions because they are preferred by the exchange medium.

When there are no ions left to replace the contaminant ions, the medium is regenerated with a suitable solution, which resaturates the medium with the appropriate ions.

Because of the required "down time," the shortest economical regeneration cycles are once per day.

The resin exchange capacity is expressed in terms of weight per unit volume of the resin.

The calculation of the breakthrough time for an ion exchange unit requires knowledge of the resin exchange capacity, the influent contaminant concentration, and the desired effluent quality.

Equipment
Typical ion exchange units consist of prefiltration, ion exchange, disinfection, storage, and distribution elements.

Sodium chloride is often used to regenerate the exchange medium in ion exchangers because of the low cost of the chemical.

However, this can result in a high sodium residual in the finished water, which may be unacceptable for individuals with salt restricted diets.

This problem can be avoided by using other regenerant materials, such as potassium chloride.

The Reverse Osmosis Process

RO can effectively remove nearly all inorganic contaminants from water.

It removes more than 70 percent of arsenic (111), arsenic (IV), barium, cadmium, chromium (111), chromium (VI), fluoride, lead, mercury nitrite, selenium (IV), selenium (VI), and silver.

Properly operated units will attain 96 percent removal rates. RO can also effectively remove radium, natural organic substances, pesticides, and microbiological contaminants.

RO is particularly effective when used in series. Water passing through multiple units can achieve near zero effluent contaminant concentrations.

Advantages

·   Removes nearly all contaminant ions and most   dissolved non-ions.

·   Relatively insensitive to flow and TDS level, and   thus suitable for small systems with a high degree   of seasonal fluctuation in water demand.

·   RO operates immediately, without any minimum   break-in period.

·   Low effluent concentration possible.

·   Bacteria and particles are also removed.

·   Operational simplicity and automation allow for   less operator attention and make RO suitable for   small system applications.

Limitations

·   High capital and operating costs.

·   Managing the wastewater (brine solution) is a potential problem.

·   High level of pretreatment is required in some cases.

·   Membranes are prone to fouling.

Process
RO removes contaminants from water using a semipermeable membrane that permits only water, and not dissolved ions (such as sodium and chloride), to pass through its pores.

Contaminated water is subject to a high pressure that forces pure water through the membrane, leaving contaminants behind in a brine solution.

Membranes are available with a variety of pore sizes and characteristics.

Equipment
Typical RO units include raw water pumps, pretreatment membranes, disinfection, storage, and distribution elements.

These units are able to process virtually any desired quantity or quality of water by configuring units sequentially to reprocess waste brine from the earlier stages of the process.

The principal design considerations for reverse osmosis units are:

·   operating pressure,

·   membrane type and pore size,

·   pretreatment requirements, and

·   product conversion rate (the ratio of the influent recovered as waste brine water to the finished water).

Electrodialysis

Electodialysis is very effective in removing fluoride and nitrate, and can also remove barium, cadmium, and selenium.

Advantages

·   All contaminant ions and most dissolved non-ions are removed.

·   Relatively insensitive to flow and TDS level.

·   Low effluent concentration possible.

Limitations

·   High capital and operating costs.

·   High level of pretreatment required.

·   Reject stream is 20-90 percent of feed flow.

·   Electrodes require replacement.

Process
The membranes adjacent to the influent stream are charged either positively or negatively, and this charge attracts counter-ions toward the membrane.

The membranes are designed to allow either positively or negatively charged ions to pass through the membrane, thus ions move from the product water stream through membrane to the two reject water streams.

Equipment
The three essential elements of the system are:

(1) a source of pressurized water,
(2) a direct current power supply, and
(3) a pair of selective membranes.
The average ion removal varies from 25 to 60 percent per stage. Multistage units can increase the efficiency of removal.

Many membrane pairs are "stacked" in the treatment vessel.

Chemicals
Fouling of membranes may limit the amount of water treated.

Fouling is caused when membrane pores are clogged by salt precipitation or by physical obstruction of suspended particulates.

Particulates, suspended in water, can be removed in pretreatment but salts that exceed their solubility product at the membrane surface must be controlled chemically by pH reduction (to reduce carbonate concentration) or chelation of metal ions (by use of phosphate, for example).

A reversal of the charge on the membranes, a process called electrodialysis reversal (EDR), helps to flush the attached ions from the membrane surface, thus extending the time between cleanings.

Editor's Note: This article was adapted from Tech Brief- a National Drinking Water Clearinghouse fact sheet.

https://www.wateronline.com/doc/the-abcs-of-ion-exchange-and-demineralization-0001

 

ROCK CLIMBING - Shepherds, in order to follow their flocks of sure-footed sheep often cover terrain that others would have bypassed. They picked up the basic skills needed to manage the steep slopes, as well as developed the rudimentary gear to make the task easier. Rock climbing is a sport renowned for its extreme physical challenges and surging adrenaline rushes. Over time, rock climbing started to be seen as a pleasurable athletic pastime. Recreational rock climbing blossomed in the early 20th century but really came into its own in the middle of the 20th century. A range of developments emerged as it became more popular as a sport.

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Rock Climbing

What is the history of rock climbing?

BY JESSIKA TOOTHMAN

Tom Cruise's opening sequence in the movie "Mission: Impossible II" is a pretty good example of what people picture when they imagine extreme recreational rock climbing.

But folks haven't always considered scaling vertical rock faces as smashing good fun.

Throughout history, people have been faced with obstacles.

Sometimes the obstacles came in the form of repressive dictators or lean growing seasons, but at other times, they were direct and tangible -- take mountains, for example.

Before cars, trains and airplanes, if someone wanted to travel from one side of a mountain range to the other, it was a lot trickier than simply navigating sharply winding roads.

Welcome to the world of hoofing it.

Speaking of hooves, to uncover early incarnations of mountaineering you simply need to determine which historic professions would have required people to putter around near the summits of mountains.

Shepherds are a good example: In order to follow their flocks of sure-footed sheep, shepherds were often forced to cover terrain that others would have bypassed for flatter lands.

By doing so, they picked up the basic skills needed to manage the steep slopes, as well as developed the rudimentary gear to make the task easier.

Pinpointing the exact inception of any sport is tricky, however, especially when you figure in the hometown pride factor -- athletic enthusiasts love having a claim to fame, and similar ideas often develop simultaneously in separate locales, leading to competing claims.

Plus, there's the matter of determining what event truly counts as a definitive start.

For instance, when does a shepherd's trek turn into sport? When he leaves the flock to the care of his sheepdog and ventures off for little side jaunt?

There's certainly been a lot of gray area as rock climbing evolved and entered its current recreational incarnation.

Further complicating the question are others: What exactly is rock climbing? And how closely is it related to mountaineering?

What different styles can it be broken down into?

But this isn't the history of some ponderous intellectual game like chess; this is rock climbing! A sport renowned for its extreme physical challenges and surging adrenaline rushes.

Rock Climbing as a Sport

Two men sometimes cited as establishing mountaineering's modern age are Michel-Gabriel Paccard and Jacques Balmat -- score one for the French -- who scaled all 15,771 feet (4,807 meters) of Mont Blanc in 1786.

Soon others followed their lead, scrambling all over the Alps trying to master the lofty summits.

Mountaineering began to capture the imaginations of many at this point, although it wasn't until 1857 that the first mountaineering club, the Alpine Club, came along.

But the club's formation still isn't typically considered the dawn of rock climbing as a sport of its own.

After all, while climbing a mountain often involves some vertical ascents, there's an awful lot of hiking in there, too.

In order to tackle the cliffs that were encountered during expeditions, mountaineers would often practice on smaller mountains and rock faces to build up their endurance and develop their abilities before setting off for the big leagues.

Eventually, enthusiasts increasingly began to enjoy these smaller climbs in and of themselves. There was less danger than on full-blown mountain peaks and less downtime in between thrilling climbs.

Plus, suitable ascents were easier to come by since not everyone who wants to get into rock climbing lives within driving distance of the Matterhorn or Mt. Kilimanjaro.

John Muir, the first president of the Sierra Club, was an early fan of rock climbing.

Story has it that in 1869 he was herding some sheep in Tuolumne Meadows in Yosemite when he meandered over to Cathedral Peak and decided to take a crack at it.

Modern rating systems are a matter of endless controversy among rock climbers, but to give you a basic idea, today the climb is generally considered to be around a Class 4 (out of 5) and is not often tackled without a rope.

Over time, rock climbing started to be seen as a pleasurable athletic pastime.

From the early activities of pioneering aerial daredevils, it has evolved to encompass a whole slew of rock-related recreation.

Recreational rock climbing blossomed in the early 20th century but really came into its own in the middle of the 20th century.

A range of developments emerged as it became more popular as a sport.

For example, various grading systems were created to rate the difficulty levels of different climbs.

Climbing styles were developed based on conditions like the terrain, the use (or lack thereof) of equipment and whether the climbing was done indoors or outdoors.

Jessika Toothman

Jessika has traveled to 47 of the 48 continental United States -- New Mexico, you're the last one left, but she hopes to visit you soon. Of course, it's helped that she's lived all across the U.S. -- in Washington, New York, Wisconsin, Colorado and her current digs, Atlanta. There, she earned two undergraduate degrees from Georgia State University, one of which is in print journalism, but after spending some time in the newspaper biz, she decided the Web was where it's at.

Besides being a staff writer and blogger for HowStuffWorks.com, Jessika enjoys painting, expanding her vegetarian recipe repertoire, walking her cat and spending afternoons by the pool. She's also a junkie for modern American literature, although she pours over nonfiction books from time to time, too. As co-captain of the How-to Stuff blog, Jessika is always willing to explore fresh topics and try new tasks, getting down in the trenches so others can reap the benefits of what she's discovered. Her plants know this all too well, for example, as Jessika's cheerful hit-or-miss gardening experiments usually end with green thumb goodness, but sometimes turn into learning episodes loaded with botanical bereavement.

https://adventure.howstuffworks.com/outdoor-activities/climbing/history-of-rock-climbing.htm