Weightlessness due to gravitational field

In summary, astronauts orbiting the Earth at 900km experience weightlessness because the gravitational field at that altitude is zero. They are in free fall, moving fast enough perpendicular to the force of gravity to maintain a constant orbit. Even though they are still affected by gravity, their tangential velocity prevents them from reaching the Earth. This is due to the balance between the force of gravity and centrifugal force from their orbital motion.
  • #1
scientict
3
0
Astronauts in a space capsule orbiting the Earth at a height of 900km experience weightlessness: hence the gravitational field due to the Earth must be zero at that altitude'.

Can someone please help ?
What does it mean?
 
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  • #2
Someone posted that gravity at the space station is about 90% as strong as it is at sea level. The astronauts are in free fall, but moving fast enough perpendicually to the force of gravity that the inwards acceleration from gravity results in their path being an orbit around the Earth at a near constant speed and distance.
 
  • #3
i still don't get it.. please explain clearly
 
  • #4
Read this: http://75.126.60.30/showpost.php?p=1466077&postcount=2
 
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  • #5
They're still experiencing gravity in an inverse square relation to their distance from the Earth's center.
However, so is their space capsule...

They're both free-falling back to the Earth with a tangential velocity that prevents them from ever actually reaching the earth.
 
  • #6
In a nutshell: Force of gravity = Centrifugal Force from spinning around the earth
 

FAQ: Weightlessness due to gravitational field

1. What is weightlessness due to gravitational field?

Weightlessness due to gravitational field, also known as microgravity, is the phenomenon experienced by objects and individuals when they are in a state of free-fall or orbit in a gravitational field. In this state, the gravitational force acting on the object is effectively canceled out by the centrifugal force of the object's motion, resulting in a feeling of weightlessness.

2. How does weightlessness affect the human body?

Weightlessness can have both positive and negative effects on the human body. Some positive effects include increased blood flow and improved bone density due to the lack of gravity's compressive effects. However, prolonged exposure to weightlessness can also lead to muscle atrophy, decreased cardiovascular health, and changes in the immune system.

3. How do astronauts train for weightlessness?

Astronauts undergo extensive training to prepare for weightlessness, including simulated microgravity environments such as parabolic flights and neutral buoyancy training. They also participate in physical fitness and resistance training programs to help maintain muscle and bone mass while in space.

4. Can objects or individuals experience weightlessness on Earth?

While it may seem like weightlessness is a phenomenon only experienced in space, it is possible to experience it on Earth. This can be achieved through parabolic flights, where an aircraft performs a series of maneuvers to create a temporary state of free-fall, or in specialized facilities such as drop towers or underwater training tanks.

5. How does weightlessness affect experiments conducted in space?

Weightlessness can have a significant impact on experiments conducted in space, as it removes the effects of gravity and allows for the study of phenomena that cannot be observed on Earth. However, it also presents challenges, such as the need for specialized equipment to keep objects and liquids in place, and the potential for microgravity-induced changes to affect the results of the experiment.

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