Angular momentum conservation
I1ω1+I2ω2=(I1+I2)ω
ω=I1+I2I1ω1+I2ω2
Loss =21I1ω12+21I2ω22−21(I1+I2)ω2
=21I1ω12+21I2ω22−21(I1+I2)(I1+I2I1ω1+I2ω2)2
=21(I1+I2)I1I2(ω1−ω2)2
Ei−Ef=2(I1+I2)I1I2(ω1−ω2)2
Two discs have moments of intertia I_1 and I_2 about their respective axes perpendicular to the plane and passing through the centre. They are…
JEE Main 2021 — Physics Mechanics
2021mcqmedium
Two discs have moments of intertia I1 and I2 about their respective axes perpendicular to the plane and passing through the centre. They are rotating with angular speeds, ω1 and ω2 respectively and are brought into contact face to face with their axes of rotation coaxial. The loss in kinetic energy of the system in the process is given by:
Official previous-year question
Held on 27 Aug 2021 · Verified 6 Jul 2026.
Options
- A
(I1+I2)I1I2(ω1−ω2)2
- B
2(I1+I2)(ω1−ω2)2
- C
2(I1+I2)I1I2(ω1−ω2)2
- D
2(I1+I2)(I1−I2)2ω1ω2
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