Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
Concepts Of Physics MCQ Edition [Volume 1]PhysicsRotational Mechanics

A diver with a moment of inertia of 6.0 kg-m ^2 about an axis passing through his centre of mass rotates about this axis at an angular speed of 2 rad/s . If the diver folds his hands and feet, reducing the moment of inertia to 5.0 kg-m ^2 , what will be the new angular speed?

Options

  1. A1.2 rad/s
  2. B2.4 rad/s
  3. C1.67 rad/s
  4. D4.8 rad/s

Correct answer

B. 2.4 rad/s

Step-by-step solution

According to the principle of conservation of angular momentum, if no external torque acts on a system, its total angular momentum remains constant. Initial angular momentum L₁ = I₁ ₁ Final angular momentum L₂ = I₂ ₂ Equating the initial and final angular momentum: I₁ ₁ = I₂ ₂ Substituting the given values: 6.0 2 = 5.0 ₂ ₂ = 12.0 5.0 = 2.4 rad/s

Practice Rotational Mechanics on Quantrex Academy →

More from Rotational Mechanics

A wheel revolves about its axis with a uniform angular acceleration. Beginning from rest, it attains 100 rev/sec in 4 seconds. Determine the angular acceleration and the angle rotaStarting from rest, a wheel is uniformly accelerated at 4 rad/s ^2 for 10 seconds. Subsequently, it rotates uniformly for the next 10 seconds, and is finally brought to rest over tDetermine the angular velocity of a body rotating with an acceleration of 2 rev/s ^2 as it completes the 5 th revolution after starting.A body rotates about a fixed axis with an angular acceleration of one radian/second/second . Determine the angle through which it rotates during the time in which its angular velocA disc of radius 10 cm rotates about its axis with an angular speed of 20 rad/s . Determine the linear speed of a point situated on the rim.A disc of radius 10 cm rotates about its axis with an angular speed of 20 rad/s . Determine the linear speed of the middle point of a radius.A disc rotates about its axis with a uniform angular acceleration of 4 rad/s ^2 . Determine the radial and tangential accelerations of a particle located 1 cm from the axis at the A block is suspended from a string wrapped on a disc of radius 20 cm , which is free to rotate about its fixed horizontal axis. If the angular speed of the disc is 10 rad/s at a pa Full Rotational Mechanics list All Concepts Of Physics MCQ Edition [Volume 1] PYQs