/sci/ - Science & Math

it weighs the same you retard

More. Sand closer to Earth's surface = stronger acceleration due to gravity

>>4566421
No it doesnt, there is some sand in the air as the hourglass is still running.

/sci/ used to have more complete, well-thought answers

it feels like recently it's just people trying to feel smart by shouting an answer

easy way to check, put an hourglass on a sensitive enough scale and flip it over

>>4566457
But the air is in the hourglass

>>4566492
why would you flip over such an expensive scale? you stupid?

>>4566483
Who gives a fuck? Is there that much more to say?

>>4566508
exactly what i mean
thank you for the example

It has the same mass, but different "weight". The sand at the bottom of the hourglass is ever so slightly closer to Earth and hence experiences a stronger force of gravity than when it is at the top of the hourglass.

>>4566535
exactly!

>>4566535
What about the sand that is being accelerated by gravity and excerts force on the hourglass as it hits the bottom.

>>4566483
>>4566579
>always expecting an elaborated answer on 4chan

>>4566581
that wouldn't give it more mass, it would just have more downwards force. i think, im no expert

>>4566613
>im no expert
It shows.
It also shows that you don't even know how to read and lack attentiveness since you're giving an answer to a question that was never asked.

>>4566624
no need for hostility man. it was a misunderstanding

>>4566651
My weakness is that I tend to be hostile towards people that aren't assertive while not agreeing with me.

It weighs more after.
1) Falling sand doesn't get recorded in weight.
2) More sand at bottom = more sand closer to Earth's core = more gravitational force between core and hourglass ((Gm1m2/r^2), where r is the distance between the core and the object. a smaller r means a stronger force, thus more weight).

>>4566664
thats understandable, we're all human.

>>4566674
why would the falling sand not count towards the weight? it is still inside the container

>>4566685
But it's not pressing down on the bottom of the hour glass.

>>4566688
but its pressing down on air that is pressing down on the bottom

>>4566695
That's not how it works lol. If you held a 50 lb ball out in front of you and then dropped it, would the floor immediately smash inward as soon as you let it go because "the ball is pushing down on the air which is pushing down on the ground?" No. The air just displaces. The amount it would actually push down on the ground, or in this case, the hourglass, is unfathomably (negligibly) small.

>>4566674
You're forgetting >>4566581

>>4566716
Shit, you're right. Well in that case it weighs the most just as the last piece of sand is hitting the bottom, because you have both 1) the acceleration of the sand forcing down on the bottom and 2) the sand all being at the bottom, being more strongly attracted by the Earth's core.

>>4566710
>is unfathomably small
But it IS.
Therefore it is heavier.

>>4566741
No, because that unfathomably (negligibly) small added amount is probably nowhere near the amount that would be added if that grain of sand were at or hitting the bottom.

Don't try to analyze individual grains of sand; analyze the center of mass.

The force of the hourglass against a scale equals the total weight of the hourglass minus the mass of the hourglass times the downward acceleration of the center of mass. The latter term is very small and, assuming a constant flow of sand, only comes into play at the moments when the sand starts and stops.

There's also a small effect from the sand getting closer to the center of earth, of course.

>>4566750
>hitting the bottom.
I thought that was what you were talking aboutt

>>4566761
And we can ignore the case where the sand is starting because when the sand starts flowing the hourglass is not on the scale at that point. So other than the distance-from-earth effect, it's really only the halting of flow that gives rise to a change in the measured weight.

>>4566762
No, you (or someone else) was talking about the air being pushed down by the falling sand and in turn pushing down on the bottom. I said that yes, an extreeeemely small amount of influence might be added because of a slight wisp of air pushing down on the glass, but most of the air would just displace, and it wouldn't be as influential as if that grain of sand were at or hitting the bottom anyway.

time to get off /sci/, thanks guys I thought I might be stuck here for too long learning from all the expertise

>>4566750
I don't think you understand physics, sonny. We don't just ignore changes because they're infinitesimally small unless you're some first year student hanging 1kg masses on springs.

>>4566794
Man, I liked /sci/ better when it was at /g/'s.

>>4566802
Hahaha and that means I "don't understand" physics? God, try harder.

It doesn't matter in the bigger picture anyway. Am I not correct in that that amount would not be nearly as much as if the grain of sanding were at or hitting the bottom?

>>4566835
You are correct in that, but completely wrong in your original statement when you said that it doesn't affect the weight.

it depends on how tall the hourglass is then!

>>4566685
Because weight isn't mass.

>>4566848
I never said it didn't affect the weight, I said the amount it affected the weight was negligibly small when compared to other instances of the scenario. At this point it's obviously just trivial interpretation differences, so why bother even arguing.

>>4566851
What's the limit of sand fall height where the falling sand and the force of it hitting the bottom cancel each other out?