Why is water heavier than it looks?

  • #1

Main Question or Discussion Point

Why?
 

Answers and Replies

  • #2
haruspex
Science Advisor
Homework Helper
Insights Author
Gold Member
32,377
4,901
I think this question belongs in the psychology section.
 
  • #3
Bobbywhy
Gold Member
1,722
47
Better Best, Welcome to Physics Forums!

How heavy, exactly, does water look?

Cheers,
Bobbywhy
 
  • #4
Well, idk. You're able to easily move it around and stuff but when you try to pick it up it takes effort.
 
  • #5
1,254
105
Well, idk. You're able to easily move it around and stuff but when you try to pick it up it takes effort.
Always slipping through your fingers?
 
  • #6
Always slipping through your fingers?
Would that make it heavy?
 
  • #7
BruceW
Homework Helper
3,611
119
Well, idk. You're able to easily move it around and stuff but when you try to pick it up it takes effort.
no, it's not easy to move around. Its inertial mass and gravitational mass are the same.
 
  • #8
Drakkith
Staff Emeritus
Science Advisor
20,702
4,384
Would that make it heavy?
Water moves around things because it is a fluid. (It is also a liquid)
To quote wiki:

In physics, a fluid is a substance that continually deforms (flows) under an applied shear stress.
How HEAVY something may be is related directly to its mass.
 
  • #9
Bobbywhy
Gold Member
1,722
47
  • #10
Water moves around things because it is a fluid. (It is also a liquid)
To quote wiki:



How HEAVY something may be is related directly to its mass.
Oh, ok. Well then can you explain that to me? Because a balloon full of air and a balloon full of water the same size basically look similar, but the one with water is much heavier. How is that so if they're taking up the same amount of space? Stupid question, I know.
 
  • #11
521
70
This may come as a surprise to you but your eyes are not scales. They detect light, not mass.
 
Last edited:
  • #12
Drakkith
Staff Emeritus
Science Advisor
20,702
4,384
Oh, ok. Well then can you explain that to me? Because a balloon full of air and a balloon full of water the same size basically look similar, but the one with water is much heavier. How is that so?
For a gas like helium in a balloon, there are FAR fewer atoms of helium that will fit in the balloon compared with water. This isn't because helium is "larger", it is because helium is a gas normally. The atoms are flying around very quickly and don't stick together at all like water does. Water molecules attract each other and are much heavier than helium atoms are, so they are much harder to turn into a gas. (Which is why water is a liquid all the way up to 100 Celsius while helium is a gas unless you cool it to around -270 Celsius)
See the following links for more.

http://en.wikipedia.org/wiki/Liquid
http://en.wikipedia.org/wiki/Gas
 
  • #13
Borek
Mentor
28,298
2,683
Because a balloon full of air and a balloon full of water the same size basically look similar, but the one with water is much heavier. How is that so if they're taking up the same amount of space?
My troll detector goes "ping". This is a question children in preoperational stage may ask - that means, up to 7 y.o.
 
  • #14
BruceW
Homework Helper
3,611
119
Oh, ok. Well then can you explain that to me? Because a balloon full of air and a balloon full of water the same size basically look similar, but the one with water is much heavier. How is that so if they're taking up the same amount of space? Stupid question, I know.
I'm going to assume no troll, and say the answer is density. You can imagine the water balloon has got more stuff inside, even though it has same volume as the air balloon. The ratio of 'stuff' to volume is density. (Or, more technically than 'stuff', I should say mass). In an equation:
[tex]density = \frac{mass}{volume}[/tex]
And the density of different materials is different.
 
  • #15
sophiecentaur
Science Advisor
Gold Member
23,993
4,155
I did wonder about this question, at first,Borek. But -
Is this question to do with the fact that, when you try to move 'through' water, you don't need to 'move it all', just to push some of it out of the way, yet, when you try to lift it (in a bucket) you need to move it all? This contrasts with a solid brick. When you lift or move a brick, you have to move all of it. Our senses are used to dealing with Newton's second law for solids and we are familiar with the extra vertical forces due to the weight of all solid objects, when lifting them. On the Moon, things are a bit different and probably a bit confusing for a while.
 

Related Threads for: Why is water heavier than it looks?

  • Last Post
Replies
19
Views
31K
  • Last Post
Replies
2
Views
2K
Replies
6
Views
6K
  • Last Post
Replies
21
Views
17K
Replies
14
Views
926
Replies
34
Views
15K
Replies
20
Views
4K
Top