Two beads each of mass m are fixed at the ends of two light rigid rods each of length l as shown in the…

Two beads each of mass m are fixed at the ends of two light rigid rods each of length l as shown in the figure. If the pivot is smooth, Calculate the ratio of translational and rotational kinetic energy of system.

  1. 8
  2. 7
  3. 6
  4. 9

Solution

Distance of centre of mass from pivot, rcm=ml+m(2l)m+m=32l
Moment of inertia of system about centre of
mass, Icm=ml22+ml22=ml22
Angular velocity of rod,ω=v2l

Velocity of centre of mass,
vcm=ω32l=v2l32l=34v
Translational kinetic energy of system,

Ktranslational =12Mtreal vcin 2

=12(2m)34v2=916mv2

Rotational kinetic energy of system, 

Krotational =12Icmω2

=12ml22v2l2=116mv2

  K1Kr=9mv216mv216=9

,

Asked in: JEE Mains - Rotational Motion - Test 3

Practice more Rotational Motion questions on Aicharya