Go Back   Physics Help Forum > High School and Pre-University Physics Help > Kinematics and Dynamics

Kinematics and Dynamics Kinematics and Dynamics Physics Help Forum

Like Tree1Likes
  • 1 Post By studiot
Reply
 
LinkBack Thread Tools Display Modes
Old Nov 11th 2017, 08:04 AM   #1
Junior Member
 
Join Date: May 2017
Location: Sri Lanka
Posts: 19
Determine the density of oil and water using a u tube

Hi, I have a question within physics practical, so I hope your help for solve this priblem.

When I do this practical my text books says we should add high density liquid first and then lower density liquid.

Also when we messure the heights of the liquids (due to pressure) if I want to change the heights to get various messurements(the messurements are taking to draw the chart) the text book says we should add the lower density liquid.

Can you say the reasons for these two situations?

In first situation why firstly add high density liquid?

In second situation why we add the lower density liquid to get various messurements? Why we can't add water to get various messurements? What is the problem?
osalselaka is offline   Reply With Quote
Old Nov 11th 2017, 09:25 AM   #2
Senior Member
 
Join Date: Apr 2015
Location: Somerset, England
Posts: 684
I assume you realise that the liquids must be immiscible and must be added gently?

What happens when you add one liquid to another in an ordinary measuring cylinder, not a U tube?

Describe both ways round. (more dense to less dense and less dense to more dense)?

Now can you answer your own question about the U tube version?
topsquark likes this.

Last edited by studiot; Nov 11th 2017 at 09:27 AM.
studiot is offline   Reply With Quote
Old Nov 11th 2017, 10:09 AM   #3
Junior Member
 
Join Date: May 2017
Location: Sri Lanka
Posts: 19
OK, according to your logic I could find the answer for the first question. In second situation mainly I can't to describe. According to the text book I add oil for messurenent. When the oil level is increasing then the oil level is going to the opposite side of the u tube. While the water is more density ,as that reason oil is goin to up of the water* so how the secon situation is correct.....
osalselaka is offline   Reply With Quote
Old Nov 12th 2017, 07:24 AM   #4
Senior Member
 
Woody's Avatar
 
Join Date: Jun 2016
Location: England
Posts: 322
The high density liquid will try to find a position below the low density liquid.
If you add the low density liquid first, the high density liquid will try to move through and/or around the low density liquid to get to the bottom, and you are likely to end up with the two liquids mixing.
__________________
~\o/~
Woody is offline   Reply With Quote
Old Nov 12th 2017, 07:29 AM   #5
Senior Member
 
Join Date: Apr 2015
Location: Somerset, England
Posts: 684
The high density liquid will try to find a position below the low density liquid.
If you add the low density liquid first, the high density liquid will try to move through and/or around the low density liquid to get to the bottom, and you are likely to end up with the two liquids mixing.
It's worse than that.

Since the liquids are immiscible, they will eventually separate.
When they do, if you add water second, you could end up with some oil on each side of the U tube, held apart by the water plug in the bottom.
studiot is offline   Reply With Quote
Old Nov 12th 2017, 07:39 AM   #6
Senior Member
 
Woody's Avatar
 
Join Date: Jun 2016
Location: England
Posts: 322
Thinking about your second point.

I think that you could do the experiment either way.
Either keep the oil constant and vary the water,
Or keep the water constant and vary the oil
(assuming both ends of the U tube are OK for adding fluid).

I am guessing that your text book has just chosen one of the options,
this makes it possible for the author of the book to define a single expected result
rather than having to try to follow the two possible outcomes.

It is sometimes useful to read on a few problems further on from the immediate question in the text book.
Sometimes the later problem presented will be something like "repeat the experiment varying the water rather than the oil...",
This then gives you a clue to the direction the book is trying to guide you and thus a clue to answering the first question.
__________________
~\o/~
Woody is offline   Reply With Quote
Old Nov 12th 2017, 08:21 AM   #7
Senior Member
 
Join Date: Apr 2015
Location: Somerset, England
Posts: 684
A sketch makes it easier to see.
Attached Thumbnails
Determine the density of oil and water using a u tube-utube1.jpg  
studiot is offline   Reply With Quote
Reply

  Physics Help Forum > High School and Pre-University Physics Help > Kinematics and Dynamics

Tags
density, determine, oil, tube, water



Thread Tools
Display Modes


Similar Physics Forum Discussions
Thread Thread Starter Forum Replies Last Post
Water Flow Through 1/2 Cu Tube bquinn22 Advanced Thermodynamics 2 Jan 6th 2015 02:14 PM
Water Flow Rate Through 1/2 Cu Tube bquinn22 Thermodynamics and Fluid Mechanics 0 Jan 5th 2015 05:00 PM
[SOLVED] Density of Oil in a U-Tube unstopabl3 Thermodynamics and Fluid Mechanics 2 May 26th 2010 09:39 PM
[SOLVED] velocity of light in tube of water r.samanta Special and General Relativity 2 Nov 5th 2009 07:12 AM
Tension and water density dh214 Kinematics and Dynamics 0 Nov 15th 2008 11:28 AM


Facebook Twitter Google+ RSS Feed