Home » Ask & Discuss » Physics
« Back to Discussion

Mechanics

Blazing goIITian

Joined:	16 Mar 2007
Post:	838

5 May 2007 11:30:36 IST

0 People liked this

1068

for jee 2008

Engineering Entrance , Medical Entrance , AIPMT , JEE Main , AIIMS , JEE Advanced , Physics , Mechanics

Hey guys and gals check this out!!!!!!!!
A sphere of mass m and radius r is projected in a viscous medium of coefficient of viscosity n (eta) with a speed v.Find the distance travelled and time taken before it stops when it is projected in :-
i)gravity free space;
ii)presence of gravity

Comments (13)

PRATIK KALANTRI

Cool goIITian

Joined: 22 Apr 2007

Posts: 91

5 May 2007 13:14:59 IST

Like 0 people liked this

in gravity free space it is 0

raja tomar

New kid on the Block

Joined: 19 Apr 2007

Posts: 25

5 May 2007 18:05:26 IST

Like 0 people liked this

how it is zero ?

U ALREADY KNOW

Blazing goIITian

Joined: 16 Mar 2007

Posts: 838

5 May 2007 18:48:34 IST

Like 0 people liked this

Well answer for the first part is not 0.

govind sukumaran

Hot goIITian

Joined: 17 Mar 2007

Posts: 104

5 May 2007 19:24:04 IST

Like 0 people liked this

in gravity free space it will travel infinitely after attainin terminal velocity......am i right?

govind sukumaran

Hot goIITian

Joined: 17 Mar 2007

Posts: 104

5 May 2007 20:02:54 IST

Like 0 people liked this

no yaar sorry,......thts wrong

U ALREADY KNOW

Blazing goIITian

Joined: 16 Mar 2007

Posts: 838

10 May 2007 21:04:37 IST

Like 0 people liked this

Hey anyone???????????????????????I myself don't know the answer
and I have to get the answer as I have a test on entire mechanics this coming tuesday.

AMZY GAWADE

New kid on the Block

Joined: 11 May 2007

Posts: 1

11 May 2007 12:01:48 IST

Like 0 people liked this

IN G FORCE:-

THE SPEED=THE FORCE ACTED ON BODY.* G CONT

& THE TIME= F* DISTANCE[S]*G CONT

ALSO THE METOD OF ANS. IS IS SAME FOR THE SEC. ONE BUT THE ANS HAS TO BE DIV.BY G CONT.

Aatish Pandit

Blazing goIITian

Joined: 3 Feb 2007

Posts: 1200

11 May 2007 13:22:14 IST

Like 1 people liked this

hey if there is no gravity at all then there is no questio of any bouyancy or any other force so only viscous force comes into play here..........

Therefore we have a retarding backward viscous force say F, acting on the sphere, which is

F=6

also F=ma, here 'a' is the retardation due to viscous force.

on comparison we have.....

ma = 6

rv --------------------(1)

but from the equation of motion "V=U+at" we have V=0, U=v and a = -a

therefore U=at=v ------------------ (2)

from (1) and (2)

t = m / (6

rv)

similarly we can calculate for distance...........

I hope my approach is right if yes then pls rate me Thanks........

Cheers....................

Aatish Pandit

Blazing goIITian

Joined: 3 Feb 2007

Posts: 1200

12 May 2007 17:55:41 IST

Like 0 people liked this

knock knock!!!!!!!!!!

someone there??????????/

U ALREADY KNOW

Blazing goIITian

Joined: 16 Mar 2007

Posts: 838

12 May 2007 20:54:02 IST

Like 0 people liked this

YA AATISH actually I was verifying your answer and I found that you are correct.Thankx.But yaar please try to find out the answer for part (ii) also i.e. time and distance in presence of gravity.

Aatish Pandit

Blazing goIITian

Joined: 3 Feb 2007

Posts: 1200

13 May 2007 14:23:21 IST

Like 0 people liked this

Hey buddy I tried for it but could not succeed.........

I think we must ask this one to experts.........

waiting for reply..........

Cheers...........

puneet chadha

Cool goIITian

Joined: 28 Apr 2007

Posts: 81

14 May 2007 19:41:29 IST

Like 0 people liked this

hi guys you have forgotten the fact that viscosity is proportional to instantaneous velocity...
use calculus n you will get the answer....
as far as second question is concerned...as the solid will fall with terminal velcoity.........so it will travel infinitely...

U ALREADY KNOW

Blazing goIITian

Joined: 16 Mar 2007

Posts: 838

14 May 2007 21:51:45 IST

Like 0 people liked this

We know that pcdagr.But still , using calculus we are not getting a perfect final answer.If you think you can do it then please post the final
answers here.

Quick Reply

Reply

	Some HTML allowed.
	Keep your comments above the belt or risk having them deleted.
	Signup for a avatar to have your pictures show up by your comment
	If Members see a thread that violates the Posting Rules, bring it to the attention of the Moderator Team