Why do Recreational Vehicle owners put cardboard or plywood covers over their wheels?

The ultraviolet rays from direct sunlight oxidizes the rubber in tires rapidly, leading to premature cracking and drying. Recreational vehicle owners sometimes buy vinyl covers for this reason.
http://www.olingertravelhomes.com/

Why do people sometimes find sand in the pockets of new blue jeans?

Conceivably, you might pick up a pair of jeans returned by a previuos customer who went to the beach, but that is highly unlikely. We aren't gamblers by nature, but we would be willing to wager a small sum that the jeans in question were stonewashed.
Stonewashed jeans are softened by rubbing against pumice stones during washing. Pumice is a soft white stone that is placed in huge washers along with jeans to be "stonewashed."
Pumice stones used in the stonewashing process sometimes disintegrate into tiny particles (or sand) that end up in the pockets of the jeans.
Obviously, pockets are the one portion of the jeans most susceptible to trapping loose pumice.
Any other sand would tend to get rinsed away with the wash water.http://www.atozbluejeans.com/ 

Why do most Buses and Trucks keep their engines idling rather than shutting them off while waiting for passengers or cargo?

The key to the answer is the fuel used in the bus or truck. If you observe carefully, you'll notice that the "idlers" are diesel-powered vehicles. We always thought that bus drivers were leaving engines idle out of laziness but these diesel-powered engines require a certain level of heat to operate most efficiently. It is cheaper to leave them running than cold starting. Diesel fuel will last last almost twice as long as gasoline when used under the same atmospheric conditions.
Idling can also be a safety issue. Most buses and many big trucks, operate with air brakes. Air brakes can't operate effectively until sufficent air pressure has built up, a process that can sometimes take up to ten minutes.
And one issue pertains specifically to school or public buses--comfort. Bus riders want and expect comfort--air conditioning in the summer and heat in the winter. Buses have a massive amount of air space that takes a longer period of time to heat or cool than an individual's automobile.http://www.eurekalert.org/pub_releases/2010-03/naos-ife0110.php

Why are Virginia, Massachusetts, Pennslyvania, and Kentucky called "Commonwealths" instead of "States"?

 These four states chose to call themselves commonwealths, yet trying to find a reason why they did so is a futile exercise. The word "state" preceeded the word "commonwealth." Etymologists argue over whether the term predated medieval Europe, but all agree that the concept of "state" was established by then. Most social scientists define a "state" could be taken over by a military dictator and still retain its "stateness."
The social philosophers of the seventeenth century argued that the government should work for the common welfare of the governed while also indicating there was no evidence that they consciously tried to separate themselves from the other colonies that deemed themselves "states." Indeed, looking over the constitutions of the four commonwealths, we see that the crafters of the documents often used "commonwealth" and "state" interchangeably.
http://en.wikipedia.org/wiki/Commonwealth#UnitedStates

Why do Geese honk repeatedly while migrating? And on long flights?

Basically, honking allows geese to maintain communication during long flights. Most importantly, it helps them to avoid midair collisions.
Also, the call and response of birds is the main reason for flying in "V-formation." The theories about the etiology of (cause) V-formations range from greater aerodynamics to superior defense against predators to better vision or auditory communication.
Another Ornithological (bird) expert told us that honking doesn't sap geese of vital energy: "They honk while exhaling, which they obviously have to do anyway."
http://birdcommunications.org/

Why do birds usually take flight against the wind?

The experts we contacted point out that, birds wings are structured like an airfoil and work best with air flowing from front to back. Feathers are arranged to overlap like shingles to aid in smooth air flow--taking off with the wind ruffling up the feathers from behind creates a lot of useless turbulence.
Also, birds with disporportionately heavy bodies for the size of their wings would probably take off against the wind more consistently--they can use all the lift they can get.
http://www.earthlife.net/birds/flight.html

Why is "$" the symbol for the American dollar?

The American dollar sign, popularly supposed to be derived from the letters U and S, is, instead a direct descendant of the Spanish abbreviation "ps" for "pesos."
So, the official position Of the Department of Treasury is that the "S" gradually came to be written over the "P" in the "pesos" abbreviation.
The "$" sign was widely used before the adoption of the United States dollar in 1785.
Spanish and Mexican coins were the main currency in many parts of the United States in the eighteenth and and much of the nineteenth centuries.
We're still not sure if the $ look more like a P and an S than a U and a S,
but at least the abbreviation of "pesos" makes more sense than a shortening of "United States."
                                  http://associatedcontent.com/article/470088/the_origin_of_the_us_dollar_sign.html

Do Snakes Sneeze?

One expert we contacted told us this: "Snakes don't sneeze with their mouths shut, but they do clear fluid from their throat with an explosive blast of air from the lungs."
Snakes don't sneeze very often, though. In fact, a few herpetologists we contacted denied that snakes sneeze at all. But another expert we contacted insisted otherwise: Snakes sneeze for the same reason as other vertebrates--to clear their respiratory passages. Snakes rarely sneeze, however, and people who keep them in captivity know that sneezing in snakes is usually a sign of respiratory illness resulting in fluid in the air passage.
http://www.answerbag.com/q_view/359084

Do Fish Pee?

Yes, of course, fish urinate. But not all fish urinate the same way. Freshwater fish must rid themselves of the water that is constanly accumulating in their bodies through osmosis. The kidneys of freshwater fish must produce exuberant amounts of dilute urine to prevent their tissues from becomming waterlogged.
Compared to their freshwater counterparts, marine fish, who lose water through osmosis, produce little urine.
http://answers.yahoo.com/question/index?qid=1006041406057

Why do you need to Supply Oxygen to a Tropical Tank when Fish are capable of Surviving Without extra oxygen in Lakes and Oceans?

The expert we contacted on this question told us this: "You have to provide oxygen to any tank that has more fish (thus higher oxygen demand) than the plants and algae in that atmosphere can supply".
Most natural bodies of water are alive with oxygen-producing plants, the plant life in a home tank is like a sprig of parsley next to a piece of halibut in a restaurant.
http://wikipedia.org/wiki/Fish_tanks#Design

Why aren't "Green cards" green?

The U.S. Immigration and Naturalization Service (INS) gave us this answer-"What know as the 'green card' used to come in a variety of different colors at different times in our history. Still referred to as 'green cards' for the same reason dismissal notices are called 'pink slips,' etc.. In each case an idea was originally associated with an actual item of respective color."
A lawful permanent resident (LPR) alien living in the United States may carry a card that is not green, but refers to it as a 'green card.'
The alien does so because those benefits came into being at the time when the card was actually green. The green card is formally known as the Alien Registration Receipt Card, form I-151 or I-151. The first receipt cards were form AR-3 and were printed on white paper.
                                   http://www.immigrationdirect.com/

What is the Liquid that forms on the top of Yogurt?

That liquidy stuff is called whey. When the bacteria that forms yogurt grows sufficiently, the milk coagulates. The proteins squeeze together and form curds, pushing out the watery whey.
Whey may be watery, but it isn't water. Whey contains sugar, minerals, some protein, and lactose. Don't waste it. Mix it back in with the rest of the yogurt. You'll be a better (nutritionally, anyway) for it.
http://aboutyogurt.com/

Do Butterflies (and other insects) sneeze or cough?

All of the entomologists contacted were positive they had the correct answer. Butterflies and other insects don't sneeze or cough. It's particularly difficult for them to sneeze, as they do not possess true noses. So then how do insects breathe?
Butterflies and other insects breathe through holes in the sides of their bodies called spiracles. Spiracles are provided with valvelike devices that keep out dust and water. Some insects, such as some flies, june beetles, lubber grasshoppers, and notably the Madagascar hissing cockroachs, make sounds for communication purposes by forcing air out though the spiracles. Hence they hiss.
http://www.planetgreen.org/

What's the deal with the grades of Architectural and Art pencils?

Here's the code: "H" stands for "Hardness" and "B" stands for "Black."
With pencils, "hard" means a pencil that yields a lighter image. "Soft" pencils provide darker images. In this case, "black means soft.
From hardest to softest, these are the grades: 9H, 8H, 7H, 6H, 5H, 4H, 3H, 2H, H, HB, F, B, 2B, 3B, 4B, 5B, 6B.
HB is the equivalent of the "regular" number 2 pencil. The grade "F" is a grade between "HB" (hard and black) and "B." A noted pencil manufacturer contacted said that "F" was originally introduced for taking shorthand, because it was "hard" enough to withstand extended use without resharpening and black enough so as to ensure that the shorthand was subsequently legible."
The "E" grades are used to designate the hardness of Filmograph leads. These leads are produced for plastic film and used in technical drawing. Filmograph leads contain no graphite and are based upon polymers and carbon black. They are used in order to prevent the written or drawn line from being smudged when the drawing is being handled. E1 is the softest grade and E4 the hardest.
http://wiki.answers.com/Q/what_are_different_pencil_grades

Why is it that what looks to us like a Half-Moon is called a Quarter-Moon by Astronomers?

Much to our surprise, when astronomers throw lunar fractions around, they are referring to the orbiting cycle of the Moon, not the appearance to us.
The Moon is half lit when it is a quarter of the way around its orbit. The count begins when the moon is in the vicinity of the sun (at "new moon" phase). "First quarter" is when the Moon has traveled one-quarter of the way around the sky from there. The Moon is full when it is halfway around the sky, and the "third quarter" or "last quarter" is when it's three-quarters of the way around its orbit. Laymen sometimes misname other lunar apparitions. Sometimes a crescent moon hanging low in the evening sky is called a "New Moon," but the moon is far from new.
the crescent Moon is some three or four days past the actual moment of New Moon, which is the instant when the center of the Moon passes between the Earth and Sun.
http://www.space.com/moon

Why do Baked Hams usually have a checkerboard pattern along the top?

Unlike a brittle skin, it's quite easy to cut superficial slices in ham, and many cooks find the pattern visually pleasing. Chances are, that scoring of ham was originally initiated for more practical reasons. Pork experts say this process began with the old-style hams that had more fat. The scoring, or slicing, of the surface was done to allow the fat to drain during cooking. Hams today are much leaner, so the scoring may be done simply for visual reasons. Since the hams are lean, it is important not to score too deep. This will cause the natural juices to run out and make the ham very dry. Occasionally you will buy a ham with a checkerboard pattern already on it. These are imprints of the netting used to hold-shape the meat during curing. Nettings (or "stockings") are used in curing of boneless hams, which tend to bulge if left to cure without "undergarments."
http://en.wikipedia.org/wiki/ham

When do Kids turn into Goats?

No exact answer could be found. Among the "experts", no definitive consensus could be reached. Some argued for months; others longer.
One expert said that kids are ready to breed when they are about seven months old and weigh about seventy-five pounds. "Kid: a goat under one year of age."
Since the definitions of "kid" vary from expert to expert, the most popular definition is thus: Baby goats are called "kids" the first year of their life. The second year they are called "yearlings," and after age two either "does" or "bucks."
Still, some veterinarians spoken to felt that once a goat can breed and bear offspring, it is inappropriate to call mama or papa a kid.
http://animals.nationalgeographic.com/animals/atoz.html

Why do plastic gallon milk containers have the counter-sunk dips on their sides?

According to dairy experts contacted about this question, those dips are there to provide structual support and strength to the container. And nothing more.
http://en.wikipedia.org/wiki/milk)bottle

What's the difference between Skim and Nonfat milk? And how do they skim the fat from whole milk?

By law, skim milk and nonfat are the same: containing less than 0.5 milkfat content. (The milk solids that are not fat must equal or exceed 8.25 percent.) In practice, all the fat possible is eliminated from the product. Any nonfat (or lowfat) milk that is shipped interstate must contain added vitamin A. Most of the vitamin A content in milk is contained in the milkfat. Most manufacturers add enough to equal the amount of vitamin found naturally in whole milk. How do they separate the fat from whole milk? Expert dairy consultans say, "It contains somewhere between 3 to 4 percent butterfat content. To obtain true skim milk, a machine called a "separator" is used. It whirls the milk around, and because the fluid and the butterfat content have different weights, centrifugal force separates the two ingredients into skim milk and cream.
http://www.dairyforall.com/different-types-of-milk.php

Why do Pigeons make a whistling sound when they take off in flight?

Those aren't pigeons' voices but rather their wings you are hearing. We are hearing the sound of air passing through the feathers that are spread wide for acceleration, beating faster for lift, and spread wide for takeoff. Although we tend to associate this kind of high-frequency noise with hummingbirds, many birds produce similar tones, not unlike the sound of whistling through the branches of trees.
http://www.pleasebekind.com/pigeon.html