GRAVITY - ITS IMPORTANCE AND REQUIREMENT

Posted by Unknown |

DO WE REALLY NEED GRAVITY?

Yes! Without it there would be no Universe as we know it. Gravity is what keeps you, and everything else, on Earth. It is the tendency of objects with mass to be attracted to each other. An object’s mass is the amount of material it contains. The bigger the mass of an object, the stronger its force of gravity.

FIVE REASONS WHY GRAVITY IS GOOD:-

·         Gravity makes things fall when they are dropped. At least you know where to start looking for your socks.

·         It is the force that keeps the water on Earth and makes the rain and snow fall to planet’s surface.

·         The Earth’s gravity holds the atmosphere in place.

·         The Sun’s gravity keeps the Earth and other planets in orbit around it.

·         Gravity keeps everything else in the Universe in orbit around some other object. Without it there would just be a chaos of floating matter.

“ESCAPE VELOCITY”:-

The speed needed to break free of an object’s gravitational pull is called “escape velocity”. Escape velocity from the Earth is 11.2 km/sec (6.96 miles/sec). Mars’s moon, Deimos, has such a small force of gravity that if you were standing on it and you jumped hard, you could achieve escape velocity.

ZERO GRAVITY:-

Zero gravity does not really mean any gravity at all – that’s impossible as there are always objects with mass exerting gravity, even in space. It is the feeling of weightlessness when a person is falling freely without ever reaching the ground. Astronauts face some problems while living in zero gravity, some of them are:-

·         Drinks must be kept in sealed containers and drunk through a straw or they’ll float off.

·         Avoid crumbly food as crumbs float away around th spacecraft and can get into everything.

·         When you sleep you have to be strapped tightly into a sleeping bag attached to the wall.

·         It’s confusing – there is no up or down in zero gravity, so ceilings, walls and floors are all the same.

·         You have to be firmly attached to a space toilet with Velcro and a good air seal so nothing floats away! The toilet is flushed with a jet of air.

·         Long-term weightlessness causes weakening of a person’s muscles bones. You need to exercise, or you will be too weak to walk out of the spacecraft when you get back to Earth.

FOUR WAYS TO ACHIEVE ZERO GRAVITY:

·         Orbit around Earth in a spacecraft.

·         Travel to the centre of the Earth.

·         Ride in a “Vomit comet” – a specially modified aircraft that zooms downwards towards the Earth.

·         Jump on a trampoline. For a fraction of a second, while you are at a second, while you are at the top of your jump, just before you start ot come back down, you experience weightlessness.

BRAIN BOXES:

GALILEO GALILEI: Italian scientist Galileo Galilei, who lived from 1564-1642, knew that there was a mysterious force making things move, but he just could not work out what it was.

ISAAC NEWTON: In 1687, English brain box Sir Isaac Newton did the Math’s and told the world it was a force called GRAVITY that made thing fall to Earth, and planets move through the night sky.

ALBERT EINSTEIN: In the early 20^th century, German-born genius Albert Einstein was developing revolutionary theories to explain gravity and the Universe. Mind-boggling stuff!

HOW MUCH WILL WE WEIGH IN OTHER HEAVENLY BODIES:

The pull of gravity varies around the Universe, so your weight will vary depending on where you are. Multiply your weight by the figure below to find out how heavy you would be in other parts of the Solar System:

SUN – multiply by 28, MERCURY – multiply by 0.38, VENUS – multiply by 0.91, MARS – multiply by 0.38, MOON – multiply by 0.17, JUPITER – multiply by 2.54, SATURN – multiply by 1.08, URANUS – multiply by 0.91, NEPTUNE – multiply by 1.19, PLUTO – multiply by 0.06.

“g”FORCE:- The g-force is the force you feel under acceleration. It is measured in “g”, but you experience it as the heavy feeling when you swoop up the curve of a roller coaster.

0 g: weightlessness

1 g: force of gravity at Earth’s surface

2-3 g: space shuttle astronauts experience between 2-3 g on launch

3 g: roller coasters are designed to not to exceed 3 g, though there are a few hair-raising exceptions.

4-6 g: fighter pilots, who often have to make sharp turns, may wear anti-g suits to protect them from the effects os high g-forces. If forces between 4-6 g are experienced for more than a few seconds a person might lose consciousness

5 g: experienced by Formula One racing drivers when braking

9 g: pilots pulling out of a dive may experiences as much as 9 g