Questions about Equivalence principle & Einstein Elevator?

[zarmewa]

Einstein inoculated general relativity with the help of equivalence principle and space elevator as shown in the following link

http://www.astronomynotes.com/relativity/s3.htm

QUESTIONS

1- What is the direction of weight [force] of a person standing on the floor of aforementioned elevator? - upward means along the direction of “g” or downward means opposite to “g”

2- Would a person feel sensation of his weight if hanging either from the ceiling of aforementioned elevator or hanging from the bottom of its floor?

3- Shouldn't a person move towards the center of elevator due the universal law of gravitation; F = GMm/d^2?

4- Is shell theorem applicable to this case?

5- What would be the spacetime Geometry inside this elevatro?

GO

__________________________
Eclectic Eccentric Khattak No.1

 

[Michael C]

1- What is the direction of weight [force] of a person standing on the floor of aforementioned elevator? - upward means along the direction of “g” or downward means opposite to “g”

The force on the person in the accelerating elevator is the same as the force on the person standing in an elevator at rest at the surface of the Earth: the floor exerts an "upwards" force on the person, the person exerts a corresponding "downwards" force on the floor.

2- Would a person feel sensation of his weight if hanging either from the ceiling of aforementioned elevator or hanging from the bottom of its floor?

Yes, just like in the elevator at rest at the surface of the Earth.

3- Shouldn't a person move towards the center of elevator due the universal law of gravitation; F = GMm/d^2?

Any gravitational attraction between the person and the elevator is negligible compared to the force of the Earth's gravity on the person, or the force resulting from the acceleration of the elevator.

4- Is shell theorem applicable to this case?

See 3 above.

5- What would be the spacetime Geometry inside this elevator?

Locally flat.

 

[zarmewa]

Thanks for your response - Great

As it is stated in the link

If a ball is dropped in the elevator at rest on the Earth, it will accelerate toward the floor with an acceleration of 9.8 meters/second2. A ball released in the upward accelerating elevator far out in space will also accelerate toward the floor at 9.8 meters/second2.

Shouldn’t the direction of a falling ball along the direction of acceleration “g” of elevator?

I mean why a ball accelerates toward the floor at 9.8 meters/second2 if released in the upward accelerating elevator far out in space?

It accelerates at same “g” but why in opposite direction to the acceleration "g" og elevator?

 

[Michael C]

Think of it this way: if you hold a ball inside the accelerating elevator, both you and the ball are accelerating with the elevator. As soon as you release the ball, it stops accelerating: the floor of the elevator now accelerates up towards the ball.

 

[zarmewa]

My question might be not clear but

Q:Why do things fall on earth?
A:Due to gravity - along the direction of "g" So

What causes the ball to fall downward toward floor when the direction of gravitational acceleration is upward?

 

[Michael C]

There may be confusion between the terms "gravitational attraction" and acceleration. When you stand on the surface of the Earth, the Earth exerts a force on you ("gravitational attraction") in a certain direction, which you call "downwards". This is directly equivalent to standing on a platform which is accelerating in the opposite direction to this force.

This article expresses it succinctly:

The key idea of general relativity, called the equivalence principle, is that gravity pulling in one direction is completely equivalent to an acceleration in the opposite direction.

 

[zarmewa]

My QUESTION is why do things fall on aforementioned floor of elevator when the direction of

1- Gravitational acceleration of elevator “g_e” is upward [9.8 m/s/s]

2- Gravitational acceleration of person “g_p” is upward [attract floor of elevator]

3- Gravitational acceleration of a ball ”g_b” is upward [attract floor of elevator]

So what causes the ball to fall downward on the floor of elevator?

 

[DrGreg]

So what causes the ball to fall downward on the floor of elevator?

It's all relative. The elevator accelerates upwards relative to the ball, so the ball accelerates downwards relative to the elevator.