Why do astronauts float in the space station?

SCIENCE FACTS(Astronaut)

Weightlessness in an orbiting spacecraft is physically identical to free-fall.An object that rests on the ground is subject to a normal force exerted by the ground. The normal force acts only on the boundary of the object that is in contact with the ground. This force is transferred into the body.The force of gravity on every part of the body is balanced by stress forces acting on that part. A weightless astronaut feels weightless due to the absence of these stress forces.But actually they are not weightless.It is gravity that keeps the space station, the astronauts, and their equipment in orbit around the Earth.An object in orbit around the Earth is falling with sideways motion that is so rapid that as it falls, the Earth’s surface moves away at just the right rate that it falls around the Earth.This is exactly what the Moon is doing in its orbit around the Earth. It is falling, but moving sideways so rapidly so that instead of approaching the Earth’s surface, it remains at an approximately fixed distance.Inside the station,astronauts and their equipments float because they and their equipments are falling — falling around the Earth — along with everything inside their spacecraft.If we look at them from outside their spacecraft,we can see they are not floating and traveling in a circle around the Earth.But inside the space station,they appear to be floating,and they experience weightlessness.
Like my Facebook page

Sonic boom

Do you know what is sonic boom?

SCIENCE FACTS(Sonic boom)

When an object traveling through the air faster than the speed of sound,it creates such a strong shock wave that it is heard on ground as a sonic boom.Sonic booms produce abundant amounts of sound energy.Sonic boom is associated with shock wave.The shock wave starts at the nose of the aircraft and ends at the tail.When a supersonic aircraft creates a series of pressure waves in front of it and hitting the waves in front before they cannot get out of the way of each other,the successive waves are forced together or getting mixed up.This is how sonic boom is created. Longer aircraft spread out their booms more than smaller ones, which leads to a less powerful boom.

Glass

How can we see through glass?

SCIENCE FACTS(Glass)

Glass is a transperant object which is an amorphous(non-crystalline) solid. The primary constituent of glass is sand(silicon dioxide,SiO₂).The atoms in a solid are tightly bound to each other.The molecules are held together with strong intermoleculer force.Therefore the molecules can not move freely and the space between them is very little.So,they do not allow light to pass through them.Light can pass through liquids and gases because the molecules of liquids and gases can move freely and a lot of space between them.Glass is manufactured by melting sand at a very high temperature and then cooling it.Therefore brittle substance is produced but glass still contains the free moving molecules of a liquid.So,light can pass through the free space between the molecules although glass itself is a solid.

Why does sun glow?

SCIENCE FACTS(Sun)

The Sun is the star at the center of the Solar System and composed of helium and hydrogen.Sunlight is the main source of energy for life on earth.Nuclear fusion at the core of the Sun produces an appreciable amount of thermal energy that makes the Sun glow.The interior of the Sun is radiative and nuclear fusion in the inner portions of the Sun has modified the composition by converting hydrogen into helium.The reactive core zone where hydrogen is converted into helium, is starting to surround the core of helium ash.This will continue and cause the sun to become red giant.This nuclear fusions produce thermal energy and that same energy reaches us as heat and light.Sunlight is mainly composed of infrared light,visible light and ultraviolet light.

Roller coaster headache

What is the reason behind roller coaster headache?

SCIENCE FACTS(Roller-coaster)

A roller coaster is an amusement ride developed for amusement parks and modern theme parks.To make them safe for the riders engineers go to extreme length.But many people who ride roller coasters end up with a medical condition called roller coaster headache.This type of ride induces up and down,to and fro,and rotatory acceleration and this sudden change in acceleration can cause roller coaster headache.This sudden change in acceleration associated with roller coaster rides causes the tearing of bridging veins.This ruptures of blood vessels in the brain are mainly caused by the movement of brain relative to the skull.Engineers,designers,managers of amusement parks, and passengers on giant roller coasters should be aware of this risk."

How can a dead rattlesnake strike accurately a reaching hand?

SCIENCE FACTS(RATTLESNAKE)

Rattlesnakes possess highly poisonous venom.The threat of envenomation, advertised by the loud shaking of the titular noisemaker at the end of their tails, deters many predators.Rattlesnake bites are the leading cause of snakebite injuries in North America.Large numbers of rattlesnakes are killed by humans in residential areas.Although rattlesnake may have been dead for as long as 30 minutes,it can still strike a person.Rattlesnakes have two organs that can sense thermal radiation.Heat-sensing pits on their faces serve as sensors of thermal radiation.When a mouse comes near to a rattlesnake ,the sensors of the snake are triggered by thermal radiation causing a reflex action in which the snake strikes the mouse.In the same way,the thermal radiation from a reaching hand can cause the same reflex action even if the snake has been dead for a while because the snake's nervous system continues to function. Older snakes possess more potent venom, and larger snakes are frequently capable of storing larger volumes of it.

Physics books

Download physics books

Concept of modern physics by Arthur beiser Fundamentals of physics by Resnick Halliday

Click the mediafire links to download Concept of modern physics by Arthur beiser and Fundamentals of physics by Resnick Halliday

1.Aurthur beiser

2.Resnick Halliday

Thanks for downloading!!!!!