If the sun attract us too.

Probably, but who cares!!

We might be lighter but I doubt we feel lighter as u say.

Originally posted by ryans
Probably, but who cares!!
that is why you are not a scientist.

Originally posted by yinyinwang
If the sun attract us too.

Tides come from the moon's action.
However, The sun also have a role in the tide's amplitude. When the moon and the sun are aligned (approximately), the tides are different from when the sun and the moon are orthogonal.

So I would say that the answer to the question:"Do we feel lighter facing the sun?" should be : Probably if you are an ocean, a sea or a big lake. If you are a person, you won't be able to notice this.

Originally posted by 1100f
Tides come from the moon's action.
However, The sun also have a role in the tide's amplitude. When the moon and the sun are aligned (approximately), the tides are different from when the sun and the moon are orthogonal.

So I would say that the answer to the question:"Do we feel lighter facing the sun?" should be : Probably if you are an ocean, a sea or a big lake. If you are a person, you won't be able to notice this.
but I would say if you are sensitive enough.

Originally posted by 1100f
Tides come from the moon's action.
However, The sun also have a role in the tide's amplitude. When the moon and the sun are aligned (approximately), the tides are different from when the sun and the moon are orthogonal.

So I would say that the answer to the question:"Do we feel lighter facing the sun?" should be : Probably if you are an ocean, a sea or a big lake. If you are a person, you won't be able to notice this.

But a body of water will not 'feel' anything! Yes it will rise but I think yinyinwang is taking an anthropogenic view here.

Originally posted by yinyinwang
but I would say if you are sensitive enough.

We can just calculate the gravitational force that the sun exerts on someone whose mass is let's say 80 kg.

When the sun is just uppward' the force that acts is given by Newton gravitational law:
F = GMm/r². Where G is the universal gravitational constant (= 6.67 10^-11 N.m².kg^-2), M is the sun mass (= 2 10³⁰kg), m is the person's weight (= 80 kg) and r is the distance between the earth and the sun (= 150 million kilometers = 1.5 10¹¹ m).

What we find is that the force is (I round the result) 0.5 N.
So if there was no sun, the weight will be 0.5 N higher. On the opposite, during the night, the weight is higher by the same amount. So the difference in weight of a person of 80 kg mass between the day and night will be 1 N. This is the weight of 100 grams of water. I don't believe that from the human sense, we can feel a difference of a half glass of water in our weight,

In my opinion, yes, but as 1100f stated, we'd be just a tiny bit lightr, so we wouldn't notice anyway. Just don't suggest IOC to only permit jumps-athlethic to be measured only at one constant hour of everyday.....

Actually, the answer is that we weigh the same on the dark side of the Earth (far from the sun) as on the light side (nearer the sun). You have to factor in the orbital centrifugal force as well as the attractions of the Earth and the Sun.

Originally posted by 1100f
I don't believe that from the human sense, we can feel a difference of a half glass of water in our weight,
What makes you believe so?

Originally posted by James R
Actually, the answer is that we weigh the same on the dark side of the Earth (far from the sun) as on the light side (nearer the sun). You have to factor in the orbital centrifugal force as well as the attractions of the Earth and the Sun.
please show how the centrifuge force works.

that is why you are not a scientist.

Yeah right. And what would you know about being a scientist.

Originally posted by 1100f
I don't believe that from the human sense, we can feel a difference of a half glass of water in our weight,

Yinyinwang: What makes you believe so?

Because u dont feel a difference when u drink a glass of water. What u might feel is the water cooling u down or the water sloshing about but u dont feel a difference in your WEIGHT!

Originally posted by James R
Actually, the answer is that we weigh the same on the dark side of the Earth (far from the sun) as on the light side (nearer the sun). You have to factor in the orbital centrifugal force as well as the attractions of the Earth and the Sun.

Also nobody's taking account of both the suns downward pull and the earths downward pull AT NIGHT!!!

Originally posted by James R
Actually, the answer is that we weigh the same on the dark side of the Earth (far from the sun) as on the light side (nearer the sun). You have to factor in the orbital centrifugal force as well as the attractions of the Earth and the Sun.

Well, when I read your post, it eas yesterday NIGHT, so because of the extra attraction toward my feet (the sun was on the other side), I had less blood in my brain.:):)
Now that it's day time, I have to say that you are perfectly right.

The difference in weight between day and night that I gave was in the case that earth do not evolve around the sun.
Since earth is rotating around the sun, the center of mass of the earth is in free fall, and the effects of the sun will be some tide effect.
I don't want to do here the calculations, but on dimensionnal grounds, I guess that the difference in weight will be something like :
2GMmR_e/r³, where R_e is the earth radius. This means that the difference will be in fact the difference that I calculated before multiplied by R_e/r which is equal to ~4 10^-5.
So the difference instead of being the weight of 100 g of water will be like the weight of 4 mg of water.

Do you know how we define the standard of weight? Did they take the time effect into consideration?

I suggest you buy gold at noon and sell at the middle of the night.
(I did not check the calculation, but accept the conclusion that there is a difference.)

Originally posted by John Connellan
Yinyinwang: What makes you believe so?

Because u dont feel a difference when u drink a glass of water. What u might feel is the water cooling u down or the water sloshing about but u dont feel a difference in your WEIGHT!
I agree that you are not concentrating on the weight change when drinking. And human may not be able to tell day from night from the feeling of weight change. But It is not difficult to do the experiment on a scale.

Originally posted by yinyinwang
I agree that you are not concentrating on the weight change when drinking. And human may not be able to tell day from night from the feeling of weight change. But It is not difficult to do the experiment on a scale.
As claimed by James R, the calculations that I have done in the begining didn't take into account that the earth is moving around the sun. If you take this motion in consideration, you find that for a 80 kg person, the difference in weight between day and night will be about 4 mg. This is very small.

btw, The price of gold is about $10 per gram. Supose that you buy 10 kg of gold (which value is about $100,000) during the day and sell it the next night, you will earn about half a cent.