Ask a Doubt
Request a call back

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

JEE Class main Answered

A uniform disc of mass M and radius R is free to rotate about a axis O passing through its rim. An insect of mass m at point A such that the line OA is the diameter of the disc as shown in figure. The insect describes a complete circle relative to disc and return to starting point A. Calculate the angle moved by the disc relative to ground.
question image
Asked by dasherbro123 | 16 Apr, 2020, 19:49: PM
answered-by-expert Expert Answer
Let ωD be the angular velocity of disc and ωi be the angular velocity of insect as shown in figure.
 
In absence of external torque, angular momentum is conserved.
 
Hence , ID ωD = Ii ωi  ......................(1)
 
where ID is moment of inertia of disc about an axis perpendicular to its plane and passing through O.
 
We have, ID = (1/2)MR2 + MR2 = (3/2)MR2
 
When the insect moving along the rim of disc and coming to same starting point after time T,
let θ be the angular displacement of disc.
 
Then angular displacement of insect (2π - θ )
 
Hence eqn.(1) is rewritten as
 
begin mathsize 14px style 3 over 2 M R to the power of 2 to the power of space end exponent cross times fraction numerator left parenthesis 2 pi space minus space theta right parenthesis over denominator T end fraction space equals space m R squared space theta over T end style
From above equation, we get begin mathsize 14px style theta space equals space fraction numerator 4 m over denominator left parenthesis space 3 M space plus space 2 m right parenthesis end fraction pi end style
Answered by Thiyagarajan K | 16 Apr, 2020, 23:00: PM

Application Videos

Concept Videos

Multiple Choice Questions Practice Test
Answered Unanswered My Questions My Answers
JEE main - Physics
a particle has initial velocity of 6i^+8j^m/s and acc of 0.8i^+0.6j^m/s2. it's speed after 10 sec is ?
Asked by swapnanemuturi | 23 Jul, 2024, 21:21: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
JEE main - Physics
a particle coverd 14m distance in 0.8 second from t=0 when the particle again coverd 14m distance
Asked by chetanjakhar86 | 20 Jul, 2024, 23:39: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
JEE main - Physics
An athlete complete one round of a circular track of radius R in 30 sec . what will be his distance and displacement at the end of 3 min 10 sec
Asked by tannujangra726 | 14 Jul, 2024, 22:02: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
JEE main - Physics
if pbar=ibar+3jbar-7kbar and q=5ibar - 2jbar+4kbar then the length of vector pqbar is
Asked by senapareddirajeshkumar8 | 13 Jul, 2024, 16:23: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
JEE main - Physics
in the given equation x= a+ bt+ ct². find the dimension of a, b, c (given x is in meters and t is in seconds)
Asked by nidhikalluthattu | 11 Jul, 2024, 20:00: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
JEE main - Physics
a vector is inclined at theta to the horizontal and it's vertical component is Y. then magnitude of that vector is
Asked by ymydheli | 10 Jul, 2024, 19:20: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
JEE main - Physics
what is dipole
Asked by manishkanna555 | 07 Jul, 2024, 10:25: AM
ANSWERED BY EXPERT ANSWERED BY EXPERT
JEE main - Physics
one car moving on a straight road covers one third of the distance with 20 km/hr and the rest with 60 km/hr . the average speed is
Asked by prachitipatil146 | 05 Jul, 2024, 20:34: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
JEE main - Physics
if in a projectile motion the maximum height is equal to a horizontal range find the angles of projection
Asked by akshara9071 | 04 Jul, 2024, 18:50: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
JEE main - Physics
a paticle moving along a circular path of radius 1m completes 2(1/4)th revolution then displacement and distance of the particle are in meter is
Asked by ammuc990 | 04 Jul, 2024, 09:51: AM
ANSWERED BY EXPERT ANSWERED BY EXPERT
My Class Videos Tests ₹ Plans Ask a Doubt
Are You a Teacher or a Parent Seeking Customised Tests? Click here
×