Category Science

Why is wire gauze used while heating a glass vessel over a flame?

Glass is a bad conductor of heat. If a glass vessel is heated directly over a flame, the heat is not readily conducted to other parts of the vessel and even at the point of contact with the flame, the inside surface does not get as hot as the outside surface.

Consequently the outside surface expands more than the inside surface and the unequal expansions cause the glass to crack.

To avoid this the glass vessel is usually heated by keeping it on a wire gauze made of a good conductor of heat such as iron or copper. This ensures that heat is transferred indirectly and slowly to the glass vessel and the vessel does not crack.

 

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Why is the nib of a fountain pen split towards the end?

The ink is stored in the barrel of the pen. When we start writing, the ink flows down and collects at the hole near the middle of the nib. When we press the nib against the paper while writing, the slit in the nib opens slightly and behaves as a very narrow tube or capillary. The ink is pulled through the tube by capillary force and flows onto the paper through the tip of the nib.

Why isn’t it possible to write on an extremely smooth surface with a ballpoint pen?

The tip of the ballpoint pen consists of a small ball which projects from a metallic socket. Fast-drying, oil-based ink is supplied to it through a narrow tube. When we write, the ball rotates and transfers the ink onto the paper. If the surface on which we want to write is very smooth, there will not roll efficiently. Consequently the ink will not get transferred to the paper. Sometimes, the ball may be rotating but the ink may not be able to adhere to the surface.

 

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Why are Mach numbers used to measure the speed of aircraft especially those flying at supersonic speed?

The speed of sound in air varies. At sea level it is about 1220 kmph but at higher altitudes, where air is cooler, it slows down becoming about 1,070 kmph at a height of 11,000 metres. Because the speed of sound changes with height, planes that fly faster than the speed of sound use a Mach number to measure their speed. The Mach number is the aeroplane’s speed divided by the speed of sound at the height the aeroplane is flying.

Mach 2 indicates a speed of twice the speed of sound. At Mach 1 the plane is flying at the speed of sound. Mach 0.5 is half the speed of sound, or subsonic.

Many fighter aircraft are capable of flying at high Mach numbers.

The unit is named after Ernst Mach, an Austrian physicist.

 

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When water is frozen in an ice tray, the outer part of the ice cubes that are formed is transparent but the inner core is opaque. Why?

The freezing of water starts at the walls of the tray and at the open surface as these are the areas in contact with a cooler material. As water is a bad conductor, the cooling process of freezing moves from outside to the inside. Water has some air dissolved in it. These air molecules occupy the spaces between the water molecules. When the water starts freezing, i.e. when liquid water changes to solid state, the air molecules are forced out from the inter-molecular spaces. They can now move only to the interior where some liquid still exists. As finally, the whole volume of water freezes, the air molecules get trapped in the middle as tiny bubbles. It is these air bubbles that make the centre of the ice cube opaque. The rest of the cube, being pure ice, is transparent.

 

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Why 2020 CD3 is called a temporary satellite?

The orbit of 2020 CD3 is unstable as it is being pulled between the gravity of the Moon and that of the Earth. So, the asteroid is expected to leave its orbit around the Earth in April. As it is on a temporary orbit around the Earth, it is considered a Temporarily Captured Object (TCO) or a temporary satellite of Earth. One it leaves its geocentric orbit around the Earth, it is expected to return to a heliocentric orbit, which is an orbit around the Sun.

What else is known about 2020 CD3?

  • Astronomers have observed 2020 CD3 only about six or seven times so far.
  • Its diameter is likely between 6.2 feet and 11.4 feet.
  • 2020 CD3 has a chaotic orbit.
  • The orbital period of 2020 CD3 around the Earth is estimated to be around 47 days
  • The orbit of 2020 CD3 shows that it entered the Earth’s orbit closer to three years ago.

How did 2020 CD3 go unnoticed for years?

Asteroids like this often go undetected due to their relatively small size.

Finding such small objects is basically an accident. And there are probably many more mini-moons orbiting the Earth that we haven’t spotted yet.

The faintness of 2020 CD# and its highly-variable orbit are also cited as reasons.

When was the last time an asteroid was found orbiting the Earth?

A three-feet-wide asteroid called 2006 RH120 orbited the Earth for 18 months between 2006 and 2007. It’s expected to return in August 2028.

 

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What is 2020 CD3?

Jupiter has 79 known moons; Saturn has 53 moons and 29 awaiting confirmation; Uranus has 27 and Neptune has 14. Even our neighbour Mars has two moons. And if you have ever felt disheartened that our our planet Earth has only one moon, while some planets have many, it is time to rejoice, albeit temporarily.

Late last month, astronomers announced that they have discovered a ‘mini-moon’, a car-sized object, orbiting the Earth. They have named it ‘2020 CD3’ for now. But this is not the type of moon that will illuminate the night sky, or be visible to the naked eye, It will not even stay there forever. Due to the instability of its path through space, the object will likely leave the Earth’s orbit sometime in April.

What exactly is this object? Let’s find out in this week’s Five Ws & One H.

Astronomers discovered a mysterious object orbiting the Earth using a 1.52-meter telescope at Mount Lemmon Observatory near Tucson, Arizona, on February 15. The Minor Planet Center, an international body that tracks asteroid discoveries, announced the find on February 25.

At first, astronomers thought the object could be a piece of junk such as a dead satellite. But as data trickled in, many realised that it was not an artificial object. It is most likely a near-Earth asteroid. (To say conclusively, astronomers would need powerful telescopes to view it.)

Asteroids are space rocks that orbit the Sun. But this asteroid orbits the Earth and that makes 2020 CD3 special. Acxcording to astronomers, it is most likely that the object was circling the Sun, when the Earth’s gravity snatched it into its orbit sometime in 2017. Since the asteroid whirls around a planet (Earth), it can be called a moon or a natural satellite. As its size is small, astronomers call it mini-moon.

Who made the discovery?

The discovery was made by Kacper Wierzchos and Theodore Pruyne, researchers for the Catalina Sky Survey (CSS). The CSS is a NASA-funded project at the University of Arizona’s Lunar and Planetary Laboratory in Tuscon, Arizona. Here researchers track near-Earth objects that could be potentially hazardous to the planet.

 

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