9super tukka sky ;)
This is a googley from resnick and halliday..
Those who can will do it in a flash otherwise keep thinking for the whole day and you wont get it ;)
Find the maximum heap (Height) that sand can make in a circle of radius of R.
Coefficient of friction of sand is k.
I dont have resnick with me.. but i did it when i was preparing for JEE. I remember this question cos I was ecstatic when I solved this one ;)
-
UP 0 DOWN 0 0 41
41 Answers
1like .. k= tanθ = h/R
so... h=kR.
[actually this k always happens to come out tanθ .. ]
9donno abt this but i feel its impossible unless k>=1 ??????????
62@ sky this tukka always works but just be a bit careful..
sometimes it is 1/tan theta also ;)
9yes i took this analogous to pressure due to water
so that the pressure of friction = pressure of water
so that k >= 1
i may ve gone crazy
62I think you have this time :D
sky's answer is correct
@celestine.. do you think friction is that high ever?
k is generally .1 to .5
so according to you we will hardly be able to make a heap of sand!
1sure bhaiya... yeah sometimes it betrays .... but then... its 'kabhi kabhi' only...
9okk now got it
i was considering k btw floor and sand ;(
now use mgsinθ = kmgcosθ for a sand particle along slope
9and bhaiyya theoretically wat i said was right i think
ie k btw floor and sand >=1
wen we consider that it behaves as a fluid this follows
62are u sure celestine?
Think again..
Think of it likethis.
what are the horzontal force on any particle on the floor which friction needs to balance out??
33hey!![1]
this q was earlier asked.. and i gave the answer[1]..
http://targetiit.com/iit_jee_forum/posts/resnic_halliday_problem_140.html
9#37
yes i think
the outer most particle will have unbalanced pressure
1Those who can will do it in a flash the statement is suggesting the ans is R but i am not getting it
62umm.. no..
and at k=0, when there is no friction then all sand should just slip.. so at k=0, height should be 0.
62haha.. you are pretty close to the answer in #5.. but there is slightly more to it ;)
1then in that case some calculation mistake b'cos previously i was getting
at k=0, when there is no friction then all sand should just slip.. so at k=0, height should be 0.