| Author |
Message |
![[Post New]](/templates/default/images/icon_minipost_new.gif) 24 Jun 2008 16:55:54 IST
|
|
|
Q. A cube of ice of edge 4 cm is placed in an empty cylindrical glass of inner diameter 6 cm. Assume that the ice melts uniformly from each side so that it always retains its cubical shape. Remembering that the ice is lighter than water, find the length of the edge of the ice cube at the instant it just leaves contact with the bottom of the glass.
P.S. this HCV , vol I , page 275 q.no 25.
Rates assured.
* edited *
|
it is not important where u stand, but in which direction u are moving |
|
|
|
24 Jun 2008 17:18:56 IST
|
|
|
Initial mass = final mass
Hence,
Which gives
So side of cube = 2x = 2.26 cm
|
"A perfect mind is a treasure unsurpassed."
"It is said that human beings have 5 senses. That's because most of them lack the 6th - common sense."
-- astatine19 --
http://astatine19.blogspot.com/
|
this reply: 5 points
(with 1 
in 1 votes ) [?]
|
|
You have to be logged on to rate
|
|
|
24 Jun 2008 17:21:40 IST
|
|
|
owa ! Thanks a ton friend !
A liitle explanation plz!
|
it is not important where u stand, but in which direction u are moving |
this reply: 0 points
(with 0
in 0 votes ) [?]
|
|
You have to be logged on to rate
|
|
|
24 Jun 2008 17:23:31 IST
|
|
|
why 4 cube into half ?
|
it is not important where u stand, but in which direction u are moving |
this reply: 0 points
(with 0
in 0 votes ) [?]
|
|
You have to be logged on to rate
|
|
|
24 Jun 2008 17:25:28 IST
|
|
|
Hmm...
initial mass is volume of cube into relative density
Final mass is Volume of water into density + remaining ice
Volume of water is Area of cylindrical base into x minus the volume of the cube submerged which is 4x3
|
"A perfect mind is a treasure unsurpassed."
"It is said that human beings have 5 senses. That's because most of them lack the 6th - common sense."
-- astatine19 --
http://astatine19.blogspot.com/
|
this reply: 0 points
(with 0
in 0 votes ) [?]
|
|
You have to be logged on to rate
|
|
|
24 Jun 2008 17:29:04 IST
|
|
|
is nt the density of ice 0.9 ?
|
it is not important where u stand, but in which direction u are moving |
this reply: 0 points
(with 0
in 0 votes ) [?]
|
|
You have to be logged on to rate
|
|
|
24 Jun 2008 17:32:57 IST
|
|
|
look u hav done wonder in secs.
But why don't u be a little less cryptic ? May be silly. But explain the steps. why 8x cube etc? I don't mind to be called dull.
But i want to undertstand.
|
it is not important where u stand, but in which direction u are moving |
this reply: 0 points
(with 0
in 0 votes ) [?]
|
|
You have to be logged on to rate
|
|
|
24 Jun 2008 17:33:03 IST
|
|
|
But the relative density of ice must be 0.9g/cc right.Can you explain why did you write 0.5 there?
|
"Nenenthedhavano naake teleedu"
|
this reply: 0 points
(with 0
in 0 votes ) [?]
|
|
You have to be logged on to rate
|
|
|
24 Jun 2008 17:40:49 IST
|
|
|
lol.. i mistook density for specific heat
no problem...
|
"A perfect mind is a treasure unsurpassed."
"It is said that human beings have 5 senses. That's because most of them lack the 6th - common sense."
-- astatine19 --
http://astatine19.blogspot.com/
|
this reply: 0 points
(with 0
in 0 votes ) [?]
|
|
You have to be logged on to rate
|
|
|
24 Jun 2008 17:41:24 IST
|
|
|
where r my other frnds ?
|
it is not important where u stand, but in which direction u are moving |
this reply: 0 points
(with 0
in 0 votes ) [?]
|
|
You have to be logged on to rate
|
|
|
24 Jun 2008 17:41:37 IST
|
|
|
concept is that ice floats with 9/10th of its volume inside water so if that
much water(9/10 of the vol of remaining ice cube) is formed it will just leave contact!!
|
this reply: 10 points
(with 2
in 2 votes ) [?]
|
|
You have to be logged on to rate
|
|
|
24 Jun 2008 17:45:12 IST
|
|
|
in that case a cubic equn comes.
|
it is not important where u stand, but in which direction u are moving |
this reply: 0 points
(with 0
in 0 votes ) [?]
|
|
You have to be logged on to rate
|
|
|
24 Jun 2008 17:47:17 IST
|
|
|
Ok, initial mass of total H2O will be equal to the final mass
Initially, volume of ice was 64 cu. cm. Mass of H2O initiall will be 64 x 0.9 gm
Finally, as per the diagram, mass of H2O will be Mass of ice plus mass of water
Mass of ice = (10X)3 x 0.9
Mass of water =  where  is the volume of ice submerged in the water
Equating, the value of 10x comes out to be 2.26cm again!!
EDIT: solved cubic eqn by scientific calc
|
"A perfect mind is a treasure unsurpassed."
"It is said that human beings have 5 senses. That's because most of them lack the 6th - common sense."
-- astatine19 --
http://astatine19.blogspot.com/
|
this reply: 5 points
(with 1
in 1 votes ) [?]
|
|
You have to be logged on to rate
|
|
|
24 Jun 2008 17:52:22 IST
|
|
|
I am posting my solution. I feel its correct but I am not getting the right answer. 
Mass of ice melted = mass of water in container
(43 - a3)0.9 = pi.32.h (where, a = edge of cube after melting of ice, h=height of water in container)
So, h=(43 - a3)/10pi
Now, as it leaves contact with the floor, means mg=buoyant force
0.9 a3 g = 1 a2 h g
Finally u get this eq-
a3 + 9.pi.a - 64=0
Now, I didnt have enuf courage to solve it  . So I used this site-
http://www.hostsrv.com/webmab/app1/MSP/quickmath/02/pageGenerate?site=quickmath&s1=equations&s2=solve&s3=basic
And according to it, a = 1.98656 cm.
PLZ correct me if I am wrong.
|
The quality of a person's life is in direct proportion to their commitment to excellence, regardless of their chosen field of endeavor.
It is during our darkest moments that we must focus to see the light.
Check out my blog at:
http://tarinbansal.blogspot.com/
Posts:
Can marks really judge a student??
Some myths about Chemical Engineering.
(A must see for every student)
Back to goiit, this time with Baby Veerappan. :D |
|
|
Moderation Team
![[Up]](/templates/default/images/icon_up.gif "[Up]"){kind=icon}
![[Thumb - cylind.jpg]](/upload/2008/6/24/0ace28e3b6cc54c8781fb705511cb210_33916.jpg_thumb)
![[Thumb - cylind.jpg]](/upload/2008/6/24/e6c7ba2f1284fede2b2ff7c6696e51e4_33916.jpg_thumb)
