Why Aren't Moon, Earth, Men Weightless Though They Are All in Freefall?

[The]

We know things in free fall are weightless. We know in a way that the Moon is in free-fall around the Earth. Only since the moon is travelling sideways at the same rate at which the earth is bending away from it, it never hits ground. However it is still free-fall.

1) So is the moon weightless? If it is, then if there are (say) astronauts on the moon, then they too are in freefall along with the moon. So would those astronauts weigh anything?

If we extend it then the Earth is effectively also in freefall around the sun in the same way that moon is around earth, then is Earth weightless too? If not why not?

2) If the earth is weightless, as its in freefall, then humans or for that matter anything on earth, a stone, a remote, a table, etc. is also in freefall around the sun along with the earth? So when in freefall, why do humans, remote, stone etc. have weight?

[Phi for All]

We know things in free fall are weightless.

 

That would only be true if there was no gravitational field. Weight measures the pull of gravity.

[StringJunky]

Gravity is a centripetal force, which means that two objects will tend to move towards each others centre of gravity, that is assuming equal velocity (same motion and same direction). The greater the ratio in mass between the two, the more force is exerted by the larger object on the smaller one, leading to the smaller object ‘falling’ faster towards the larger object, relative to the larger object ‘falling’ to the smaller one. As the ratio between the two rises, this increases the relative ‘weight’ of the smaller object - as measured on the surface of the larger object. A 1Kg weight on Earth weighs about 1/7^th of that on the Moon... it falls relatively slower towards the Moon’s centre of gravity compared to on Earth.

Edited March 24, 2016 by StringJunky

[J.C.MacSwell]

If you feel no gravitational counteracting acceleration you are weightless in your frame of reference.

 

If you are orbiting the Earth you are weightless. If you are in free fall you are weightless.

 

If you are on the Moon you weigh about 1/6 what you weigh on Earth.

Edited March 24, 2016 by J.C.MacSwell

[Janus]

We know things in free fall are weightless. We know in a way that the Moon is in free-fall around the Earth. Only since the moon is travelling sideways at the same rate at which the earth is bending away from it, it never hits ground. However it is still free-fall.

1) So is the moon weightless? If it is, then if there are (say) astronauts on the moon, then they too are in freefall along with the moon. So would those astronauts weigh anything?

If we extend it then the Earth is effectively also in freefall around the sun in the same way that moon is around earth, then is Earth weightless too? If not why not?

2) If the earth is weightless, as its in freefall, then humans or for that matter anything on earth, a stone, a remote, a table, etc. is also in freefall around the sun along with the earth? So when in freefall, why do humans, remote, stone etc. have weight?

To put it in simple terms, an astronaut on the Moon is weightless with respect to the Earth due to his shared orbit with the Moon around the Earth. However, the Moon has its own gravitational field, And he is not weightless with respect to it.

Similarly, Someone standing on the Earth is weightless with respect to the Sun, but is not weightless with respect to the Earth and its gravity.

[Sensei]

We know things in free fall are weightless. We know in a way that the Moon is in free-fall around the Earth. Only since the moon is travelling sideways at the same rate at which the earth is bending away from it, it never hits ground. However it is still free-fall.

1) So is the moon weightless? If it is, then if there are (say) astronauts on the moon, then they too are in freefall along with the moon. So would those astronauts weigh anything?

If we extend it then the Earth is effectively also in freefall around the sun in the same way that moon is around earth, then is Earth weightless too? If not why not?

2) If the earth is weightless, as its in freefall, then humans or for that matter anything on earth, a stone, a remote, a table, etc. is also in freefall around the sun along with the earth? So when in freefall, why do humans, remote, stone etc. have weight?

You're probably mixing word "weight" with "mass".

 

Weight is force:

W=m*g

https://en.wikipedia.org/wiki/Weight

In unit Newtons.

 

While mass is in unit kilograms.

https://en.wikipedia.org/wiki/Mass

 

g changes with distance to object creating gravitation:

g=G*M/r^2

 

Gravitational force on the Moon caused by Earth (r=~384,000,000 m) (or Sun r=~150*10^9 m) is meaningless, as majority of force is caused by the Moon's mass (with r equal radius of the Moon).

Meaningless, doesn't mean not existing. That's why there are tides caused by the Moon, and tides caused by the Sun.

https://en.wikipedia.org/wiki/Tide

 

Astronaut, on the Moon, will be able to jump much further, than on the Earth, using the same force created by his legs/body. Different result in length of jump.

(Jumping on asteroid is not advised, as you can fly away, and never be able to come back, unless you have jet pack)

 

You can find distance from Earth to Moon, or Earth to Sun, or any other object, where force created by one object cancels perfectly with force created by other object.

Edited March 25, 2016 by Sensei

[The]

To put it in simple terms, an astronaut on the Moon is weightless with respect to the Earth due to his shared orbit with the Moon around the Earth. However, the Moon has its own gravitational field, And he is not weightless with respect to it.

Similarly, Someone standing on the Earth is weightless with respect to the Sun, but is not weightless with respect to the Earth and its gravity.

 

That made a lot of sense. Thx