Today I Learn

2021-07-06 15:04:43 How do Planes fly?

If you've ever watched a jet plane taking off or coming in to land, the first thing you'll have noticed is the noise of the engines. Jet engines, which are long metal tubes burning a continuous rush of fuel and air, are far noisier (and far more powerful) than traditional propellor engines. You might think engines are the key to making a plane fly, but you'd be wrong. Things can fly quite happily without engines, as gliders (planes with no engines), paper planes, and indeed gliding birds readily show us.

If you're trying to understand how planes fly, you need to be clear about the difference between the engines and the wings and the different jobs they do. A plane's engines are designed to move it forward at high speed. That makes air flow rapidly over the wings, which throw the air down toward the ground, generating an upward force called lift that overcomes the plane's weight and holds it in the sky. So it's the engines that move a plane forward, while the wings move it upward.

Four forces act on a plane in flight. When the plane flies horizontally at a steady speed, lift from the wings exactly balances the plane's weight and the thrust exactly balances the drag. However, during takeoff, or when the plane is attempting to climb in the sky (as shown here), the thrust from the engines pushing the plane forward exceeds the drag (air resistance) pulling it back. This creates a lift force, greater than the plane's weight, which powers the plane higher into the sky. Newton's third law of motion explains how the engines and wings work together to make a plane move through the sky. The force of the hot exhaust gas shooting backward from the jet engine pushes the plane forward. That creates a moving current of air over the wings. The wings force the air downward and that pushes the plane upward. @TodayILearn Open / Comment

2021-07-06 03:52:55 Multi-colored holes?

Black holes aren’t black. They’re very dark, sure, but they aren’t black.

They glow, slightly, giving off light across the whole spectrum, including visible light.

This radiation is called “Hawking radiation” after the former Lucasian Professor of Mathematics at Cambridge University Stephen Hawking, who first proposed its existence.

Because black holes are constantly giving off this radiation, and therefore losing mass, they will eventually evaporate if they don’t have another source of mass to sustain them.

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2021-07-06 03:18:58 @TodayILearn Open / Comment

2021-07-05 05:45:36 ​​What is Sea Snot and How is it formed?

A slimy layer of grey or green sludge formed when algae are overloaded with nutrients is called sea snot.

It is a marine mucilage and is harmful to the water bodies.

When algae are overloaded with nutrients as a result of water pollution and climate change, it begins to create a thick slimy layer on the surface of the water.

This layer is colloquially known as sea snot. These algae feast and grow in warm and nutrient-rich water.

With the increased water pollution, global warming and deteriorating climatic condition, the overall situation of water bodies across the globe are being affected.

Considering sea snot, it also leaves a severe impact on marine life.

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2021-07-03 07:47:31 How do Movie Projectors Work?

A movie projector is a device that continuously moves film along a path so that each frame of the film is stopped for a fraction of a second in front of a light source. The light source provides extremely bright illumination that casts the image on the film through a lens onto a screen. The key element in a projector is the light source. Carbon arc lamps have been used since the early 1900s but have a very short life. Xenon bulbs are the most commonly used lamps today. Xenon is a rare gas with certain properties that make it especially suited for use in projectors.

As the focused light leaves the lamphouse and enters the projector, it is intercepted by the shutter. The shutter is a small, propeller-like device that rotates 24 times per second. Each blade of the shutter blocks the path of the light as it comes to a certain point in its revolution. This blacking out is synchronized with the advancement of the film so that the light doesn't project the fraction of a second when the film is moving from one frame to the next. Without it, the film would seem to flicker or have faint impressions of the images out of sync. Many projectors use double shutters that rotate in opposite directions. This causes the light to be cut off from both the top and bottom of each frame, further reducing the possibility of flicker.

Before the light gets to the film, it also passes through an aperture gate. The aperture gate is a small, removable metal frame that blocks the light from illuminating anything but the part of the film that you want to see on the screen. Two good examples of unwanted images would be the sprocket holes and audio information along the sides of the film. Aperture gates come in a variety of sizes that correspond to the screen format of the movie. @TodayILearn Open / Comment

2021-07-03 07:46:57 @TodayILearn Open / Comment

2021-07-01 04:59:18 Open / Comment

2021-07-01 04:59:17 ​​What is Magnus Effect and What are it’s Applications?

Have you ever wondered how a football player puts a goal bending the ball around a five-person wall?

Well, the answer is Magnus’ Effect.

Curving the ball in the air is not as easy as it looks. There are some physics concepts that make it possible.

Magnus effect occurs on spinning objects that are spherical or cylindrical. The effect that we can observe is that the moving spinning object bends away from the intended direction of travel.

The spin of the object alters the airflow around the body and by the conservation of momentum it causes the Magnus effect.

The effect is named after the German physicist Heinrich Gustav Magnus, who described the effect in 1852.

Other scientists like Sir Issac Newton have explained this effect before Magnus, but it was Magnus who got honoured.

Magnus effect is mainly applied in games like football, golf, cricket, tennis, baseball and many more.

This concept is important in understanding the physics behind many ball sports. Some aircraft have been built that use Magnus effect to lift using a rotating cylinder at the front of a wing, this allows the flight at lower horizontal speeds.

It is used in external ballistics. The combined sideways wind component of the wind causes a Magnus force to act on the bullet.

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2021-06-29 20:06:03 @TodayILearn Open / Comment

2021-06-29 20:05:59 ​​Why do Medical Facilities use White Linens?

Have you noticed how prominent white linens are in the medical industry?

From doctor’s offices to dentists, hospitals, and more, white linens are commonplace.

But why?

White linens are the clear and perfect choice for medical facilities for a variety of reasons.

Fresh and crisp white linens look appealing and stylish to the eye.

They can give a sense of cleanliness and sterility. Not only that, but studies have shown that patients are more likely to trust doctors who wear white lab coats over formal clothing.

You might be surprised to learn that white linens are actually easier to clean than linens of any other color.

Colorful linens are more challenging as you have to sort them to determine which fabrics could bleed.

White linens don’t need to be sorted, and laundry providers don’t have to worry about any color bleeding or fading. Instead they can focus solely on what matters most – getting your linens as hygienically clean as possible.

White hospital linens make it easier for nurses and other medical staff to swiftly identify issues with their patients.

White healthcare linens are the quickest to visually reveal bleeding or other bodily fluids and injury coming from a patient. Not only that but, because it’s so easy to identify injuries, dirt, and other stains on white sheets, medical personnel will better know when it’s time to change the sheets.

Patients will feel more comfortable knowing they are laying on clean sheets because they can see them for themselves.

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