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Question: Answered & Verified by Expert
A stationary horizontal disc is free to rotate about its axis. When a torque is applied on it, its kinetic energy as a function of θ, where θ is the angle by which it has rotated, is given as kθ2. If its moment of inertia is I then the angular acceleration of the disc is:
PhysicsRotational MotionJEE MainJEE Main 2019 (09 Apr Shift 1)
Options:
  • A 2kIθ
  • B k2Iθ
  • C k4Iθ
  • D kIθ
Solution:
1576 Upvotes Verified Answer
The correct answer is: 2kIθ
Kinetic Energy =kθ2
12Iω2=kθ2
ω2=2kθ2I
Differentiate both side w.r.t. θ .
2ωdωdθ=4kθI
ωdωdθ=2kθI
α=2kθI

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