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garzat5774

How birds fly | Sciencelearn Hub - 0 views

sciencelearn.org.nz/...How-birds-fly

birds

shared by garzat5774 on 03 Dec 14 - No Cached
  • Birds have many physical features, besides wings, that work together to enable them to fly. They need lightweight, streamlined, rigid structures for flight. The four forces of flight – weight, lift, drag and thrust – affect the flight of birds.
  • Flying birds have: lightweight, smooth feathers – this reduces the forces of weight and drag a beak, instead of heavy, bony jaws and teeth – this reduces the force of weight an enlarged breastbone called a sternum for flight muscle attachment – this helps with the force of thrust light bones – a bird’s bones are basically hollow with air sacs and thin, tiny cross pieces to make bones stronger – this reduces the force of weight a rigid skeleton to provide firm attachments for powerful flight muscles – this helps with the force of thrust a streamlined body – this helps reduce the force of drag wings – these enable the force of lift.
  • WingsThe shape of a bird’s wing is important for producing lift. The increased speed over a curved, larger wing area creates a longer path of air. This means the air is moving more quickly over the top surface of the wing, reducing air pressure on the top of the wing and creating lift. Also, the angle of the wing (tilted) deflects air downwards, causing a reaction force in the opposite direction and creating lift.Larger wings produce greater lift than smaller wings. So smaller-winged birds (and planes) need to fly faster to maintain the same lift as those with larger wings.Wing loading tells you how fast a bird or plane must fly to be able to maintain lift: wing loading = weight/wing area (kilograms per square metre).A smaller wing loading number means the bird/plane can fly more slowly while still maintaining lift and is more manoeuvrable.
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  • GlidingWhen a bird is gliding, it doesn’t have to do any work. The wings are held out to the side of the body and do not flap. As the wings move through the air, they are held at a slight angle, which deflects the air downwards and causes a reaction in the opposite direction, which is lift. But there is also drag (air resistance) on the bird’s body, so every now and then, the bird has to tilt forward and go into a slight dive so that it can maintain forward speed.
  • SoaringSoaring flight is a special kind of glide in which the bird flies in a rising air current (called a thermal). Because the air is rising, the bird can maintain its height relative to the ground. The albatross uses this type of soaring to support its multi-year voyages at sea.
  • FlappingBirds’ wings flap with an up-and-down motion. This propels them forward. The entire wingspan has to be at the right angle of attack, which means the wings have to twist (and do so automatically) with each downward stroke to keep aligned with the direction of travel.
  • Birds obtain thrust by using their strong muscles and flapping their wings. Some birds may use gravity (for example, jumping from a tree) to give them forward thrust for flight. Others may use a running take-off from the ground.
  • Different birds have different adaptive features to meet their flight needs: Some birds are small and can manipulate their wings and tail to manoeuvre easily, such as the fantail (pīwakawaka). The hawk, with its large wingspan, is capable of speed and soaring. Gannets and seabirds are streamlined to dive at high speeds into the ocean for fish. Godwits, although small, are equipped to fly long distances.
    • garzat5774
      garzat5774 on 03 Dec 14
       
      birds have some chacteristics that help them fly, birds are light weighted they have light feathers insted of heavy ones that add more weight to their bodys, they also have a beak insted of jaws that also add weight to their boddys, thay have hollow bones in their body that means that the bone has nothing inside it
    • garzat5774
      garzat5774 on 03 Dec 14
       
      birds get ready to fly by flapping their wings, some birds use "gravity" to take of some run and they jump just like an airplane and others jump from a tree and then start flapping their winds
guzman5862

The Healing Properties of Tears: 7 Good Reasons to Cry Your Eyes Out - Beyond Blue - 0 views

www.beliefnet.com/...ays-tears-and-crying-heal.html

cry eyes reasons works facts

shared by guzman5862 on 10 Nov 14 - No Cached
  • 1. Tears help us see. Starting with the most basic function of tears, they enable us to see. Literally. Tears not only lubricate our eyeballs and eyelids, they also prevent dehydration of our various mucous membranes. No lubrication, no eyesight. Writes Bergman: “Without tears, life would be drastically different for humans–in the short run enormously uncomfortable, and in the long run eyesight would be blocked out altogether.”
  • 2. Tears kill bacteria. No need for Clorox wipes. We’ve got tears! Our own antibacterial and antiviral agent working for us, fighting off all the germs we pick up on community computers, shopping carts, public sinks, and all those places the nasty little guys make their homes and procreate. Tears contain lysozyme, a fluid that the germ-a-phobic dreams about in her sleep, because it can kill 90 to 95 percent of all bacteria in just five to 10 minutes! Which translates, I’m guessing, to three months’ worth of colds and stomach viruses.
  • 3. Tears remove toxins. Biochemist William Frey, who has been researching tears for as long as I’ve been searching for sanity, found in one
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  • study that emotional tears–those formed in distress or grief–contained more toxic byproducts than tears of irritation (think onion peeling). Are tears toxic then? No! They actually remove toxins from our body that build up courtesy of stress. They are like a natural therapy or massage session, but they cost a lot less!
  • 4. Crying can elevate mood. Do you know what your manganese level is? No, neither do I. But chances are that you will feel better if it’s lower because overexposure to manganese can cause bad stuff: anxiety, nervousness, irritability, fatigue, aggression, emotional disturbance and the rest of the feelings that live inside my happy head rent-free. The act of crying can lower a person’s manganese level. And just like with the toxins I mentioned in my last point, emotional tears contain 24 percent higher albumin protein concentration–responsible for transporting many small molecules (which has to be a good thing, right?)–than irritation tears.
  • 5. Crying lowers stress. Tears really are like perspiration in that exercising and crying both relieve stress. For real. In his article, Bergman explains that tears remove some of the chemicals built up in the body from stress, like the endorphin leucine-enkaphalin and prolactin, the hormone I overproduce because of my pituitary tumor that affects my mood and stress tolerance. The opposite is true too. Bergman writes, “Suppressing tears increases stress levels, and contributes to diseases aggravated by stress, such as high blood pressure, heart problems, and peptic ulcers.
  • 6. Tears build community. In her “Science Digest” article, writer Ashley Montagu argued that crying not only contributes to good health, but it also builds community. I know what you’re thinking: “Well, yeah, but not the right kind of community. I mean, I might ask the woman bawling her eyes out behind me in church what’s wrong or if I can help her, but I’m certainly not going to invite her to dinner.” I beg to differ. As a prolific crier, especially on video, I always come away astounded by the comments … the resounding support of people I know all that well, and the level of intimacy exchanged among them. Read for yourselves some of the comments on both my self-esteem video and my recent death and dying video and you’ll appreciate my point. Tears help communication and foster community.
  • 7. Tears release feelings. Even if you haven’t just been through something traumatic or are severely depressed, the average Jo goes through his day accumulating conflicts and resentments. Sometimes they gather inside the limbic system of the brain and in certain corners of the heart. Crying is cathartic. It lets the devils out. Before they wreak all kind of havoc with the nervous and cardiovascular systems. Writes John Bradshaw in his bestseller “Home Coming”: “All these feelings need to be felt. We need to stomp and storm; to sob and cry; to perspire and tremble.” Amen, Brother Bradford!
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