Register to reply

Water, paper towel and energy

by tony873004
Tags: energy, paper, towel, water
Share this thread:
tony873004
#1
Sep18-09, 08:05 PM
Sci Advisor
PF Gold
P: 1,542
If you dip a paper towel into water, the water absorbs up the paper towel. These molecules are gaining height, and hence mgh is increasing. Where does the energy come from to lift the water molecules?
Phys.Org News Partner Physics news on Phys.org
Step lightly: All-optical transistor triggered by single photon promises advances in quantum applications
The unifying framework of symmetry reveals properties of a broad range of physical systems
What time is it in the universe?
DaleSpam
#2
Sep18-09, 08:11 PM
Mentor
P: 17,330
From the energy required to manufacture the paper.
bp_psy
#3
Sep18-09, 10:47 PM
P: 452
http://en.wikipedia.org/wiki/Capillary_action

tony873004
#4
Sep19-09, 12:20 PM
Sci Advisor
PF Gold
P: 1,542
Water, paper towel and energy

Thanks!
Andy Resnick
#5
Sep19-09, 02:57 PM
Sci Advisor
P: 5,523
Here's a twist- what happens if you take away gravity? The answer is not so simple, and relates to how to grow food in space.
Pyro Ninja
#6
Sep21-09, 06:31 PM
P: 7
So, if the energy required to lift the water through capillary action, is coming from the
inter-molecular forces, then why aren't these forces being 'used up' very slightly as they convert their energy into the gaining of height by the water molecules?
willem2
#7
Sep22-09, 01:17 AM
P: 1,398
The forces aren't 'used up'. Onlly energy is used up. you can get energy out of water and a paper towel by letting the towel get wet. you have to spend energy to get the water out of the towel again. (pressing or heating)
Andy Resnick
#8
Sep22-09, 07:51 AM
Sci Advisor
P: 5,523
Quote Quote by Pyro Ninja View Post
So, if the energy required to lift the water through capillary action, is coming from the
inter-molecular forces, then why aren't these forces being 'used up' very slightly as they convert their energy into the gaining of height by the water molecules?
Capillary rise coverts surface energy into gravitational potential energy. When the liquid stops rising, the increase in potential energy is balanced by the loss of surface energy from wetting.


Register to reply

Related Discussions
Fixing an Xbox360 with a towel Computing & Technology 9
Dark energy a furphy, says new paper Cosmology 50
Energy loss converting water to hydrogen then back to water General Physics 2
What causes the snapping sound when a towel is snapped? General Physics 5