Q104 / 150 · MHT CET 2016 · Physics

A ring and a disc roll on the horizontal surface without slipping with same linear velocity. If both have same mass and total kinetic energy of the ring is 4 J then total kinetic energy of the disc is

  • Correct answer
    A
    3 J
  • B
    4 J
  • C
    5 J
  • D
    6 J

Solution

Total K.E of the rolling disc or ring is given by.
K.E=12mv2+12Iω2
For ring and disk, translational kinetic energy 12 mv2 is constant.
Rolling K.E. of disc is 14 mR2ω2
Rolling K.E. of ring is 12 mR2ω2
As for ring, 4 J=12 mv2+12mR2ω2
∴ mR2ω2=4 J
For disc 12 mR2ω2+14mR2ω2=42+44 J=2+1 J=3 J

Hence, the correct answer is option: 'A'.

Relevant Questions