Ask a Doubt
Request a call back

Join NOW to get access to exclusive study material for best results

CBSE Class 11-science Answered

A Uniform Disc of diameter R/2 is put over another uniform disc of radius R of same thickness and Density. The peripheries of the two discs touch each other. The Centre of Mass of the system from centre of the big disc is?
Asked by adipadmakarri | 25 Sep, 2021, 11:18: AM
Expert Answer
As per the given statement " peripheries of discs are touching each other ",
it is assumed that the discs are positioned as shown in figure.
 
Let A ( R, h/2 ) be the centre of mass of bigger disc and B( R/2, 3h/2) be the centre of
mass of smaller disc as per the assumed Coordinates axes as shown in figure .
 
Where R is radius of bigger disc and h is common thickness of discs .
 
Since both discs have same density and thickness , mass of disc is prportional to radius of disc .
 
Let M be mass of bigger disc and m is mass of smaller disc .
 
( M / m ) = R2 / ( R/2)2 = 4   i.e. M = 4 m 
 
X-coordinate of centre of mass of combined discs,  x  =  [ m / ( m+M) ] (R/2) + [ M / ( m+M) ] (R) 
 
X-coordinate of centre of mass of combined discs,  x = R [ (1/10) + (4/5) ]  = 0.9 R
 
Y-coordinate of centre of mass of combined discs,  y  =  [ m / ( m+M) ] (3h/2) + [ M / ( m+M) ] (h/2) 
 
Y-coordinate of centre of mass of combined discs,  y = h [ (3/10) + (4/10) ]  = 0.7 h
 
Hence , centre of mass of combined discs is at  ( 0.9 R , 0.7 h ) 
 
Distance d between centre of mass of bigger disc and that of combined discs is given as
 
begin mathsize 14px style d space equals space square root of open parentheses 0.9 space minus space 1 close parentheses squared R squared space plus space left parenthesis 0.7 space minus space 0.5 right parenthesis squared h squared end root space equals space square root of 0.01 space R squared space plus space 0.04 space h squared end root end style
Answered by Thiyagarajan K | 25 Sep, 2021, 02:01: PM

Concept Videos

Multiple Choice Questions Practice Test Subjective Questions Webinar Subjective Questions Pre Board Assessment
Answered Unanswered My Questions My Answers
CBSE 11-science - Physics
A Uniform Disc of diameter R/2 is put over another uniform disc of radius R of same thickness and Density. The peripheries of the two discs touch each other. The Centre of Mass of the system from centre of the big disc is? (I asked this question before but the answer was wrong. They took the Radius as R/2 while it is the Diameter)
Asked by adipadmakarri | 26 Sep, 2021, 06:08: PM
ANSWERED BY EXPERT
CBSE 11-science - Physics
A Uniform Disc of diameter R/2 is put over another uniform disc of radius R of same thickness and Density. The peripheries of the two discs touch each other. The Centre of Mass of the system from centre of the big disc is?
Asked by adipadmakarri | 25 Sep, 2021, 11:18: AM
ANSWERED BY EXPERT
CBSE 11-science - Physics
a stone is tied to one end of a string and rotating in a vertical circle. what is the difference in tension of the lowest and highest point of the vertical circle
Asked by deekshikap2004 | 23 Jan, 2021, 10:14: AM
ANSWERED BY EXPERT
CBSE 11-science - Physics
what is centre of mass??
Asked by akhileshkumarsinghbgw | 26 Jan, 2019, 01:34: PM
ANSWERED BY EXPERT
CBSE 11-science - Physics
What do you understand by a rigid body?
Asked by Topperlearning User | 04 Aug, 2014, 01:09: PM
ANSWERED BY EXPERT
CBSE 11-science - Physics
Give four examples of a rigid body in pure rotation?
Asked by Topperlearning User | 04 Aug, 2014, 01:15: PM
ANSWERED BY EXPERT
CBSE 11-science - Physics
If a ball or a wheel is made to slide down an inclined plane, what kind of motion can it exhibit?
Asked by Topperlearning User | 04 Aug, 2014, 01:15: PM
ANSWERED BY EXPERT
CBSE 11-science - Physics
Is it necessary that there should be mass at the centre of mass of a system?
Asked by Topperlearning User | 04 Aug, 2014, 01:24: PM
ANSWERED BY EXPERT
CBSE 11-science - Physics
What will be the position of centre of mass in case of a plane lamina of the shape of a rectangle?
Asked by Topperlearning User | 04 Aug, 2014, 01:26: PM
ANSWERED BY EXPERT
CBSE 11-science - Physics
What is the centre of mass of a rigid body?
Asked by Topperlearning User | 04 Aug, 2014, 02:05: PM
ANSWERED BY EXPERT
My Class Videos Tests ₹ Plans Ask a Doubt