Sign in
12thPass logo
New chatPYQ LibraryDoubtsRank report
Sign in to see Recents

Your guest activity stays on this device

Sign in to save progress →
Sign in

Rotational Motion question

2012 · Q104
Guest · filters and generic practice availableBrowsing as a guest · PYQ filters and generic practice are available. Sign in only for personalised features and saved progress.
  1. PYQ Library
  2. /NEET
  3. /Physics
  4. /Rotational Motion
  5. /2012 · Q104

Rotational Motion question

2012 · Q104

NEETPhysicsRotational MotionMCQ+4 / −1
A circular platform is mounted on a frictionless vertical axle. Its radius R = 2 m and its moment of inertia about the axle is 200 kg m2. It is initially at rest. A 50 kg man stands on the edge of the platform and begins to walk along the edge at the speed of 1 ms−-−1 relative to the ground. Time taken by the man to complete one revolution is
  1. A
    π\piπ s
  2. B
    3π2{{3\pi } \over 2}23π​ s
  3. C
    2π\piπ s
  4. D
    π2{\pi \over 2}2π​ s
View written solutionFree

Correct answer: C

Using conservation
Li = 0 (Initial moment)
Lf = mvR – Iω\omega ω (Final moment)

According to the conservation of momentum
Li = Lf

⇒\Rightarrow⇒ mvR – I.ω\omega ω = 0

mvR = I.ω\omega ω

ω=(12)\omega = \left( {{1 \over 2}} \right)ω=(21​)

(v+ωR)t=2πR\left( {v + \omega R} \right)t = 2\pi R(v+ωR)t=2πR

t(1+12×2)=2π×2t\left( {1 + {1 \over 2} \times 2} \right) = 2\pi \times 2t(1+21​×2)=2π×2

t = 2π\pi π sec.

PreviousNext

More from Rotational Motion

  • When a mass is rotating in a plane about a fixed point, its angular momentum is directed along2012 · MCQ
  • A car of mass 1000 kg negotiates a banked curve of radius 90 m on a frictionless road. If the banking angle is 45o, the speed of the car is2012 · MCQ
  • ABC is an equilateral triangle with O as its centre. F1​,F2​ and F3​ represent three forces acting along the sides AB, BC and AC respectively. If the total torque about O is… Includes diagram2012 · MCQ
  • A small mass attached to a string rotates on a frictionless table top as shown. If the tension in the string is increased by pulling the string causing the radius of the circular motion to decrease by a factor of 2, the kinetic energy of… Includes diagram2011 · MCQ
  • The instantaneous angular position of a point on a rotating wheel is given by the equation θ(t)=2t3−6t2 The torque on the wheel becomes zero at2011 · MCQ
  • The moment of inertia of a thin uniform rod of mass M and length L about an axis passing through its midpoint and perpendicular to its length is I0. Its moment of inertia about an axis passing through one of its ends and perpendicular to…2011 · MCQ
  • A thin circular ring of mass M and radius r is rotating about its axis with constant angular velocity ω. Two objects each of msass m are attached gently to the opposite ends of a diameter of the ring. The ring now rotates with…2010 · MCQ
  • A solid cylinder and a hollow cylinder, both of the same mass and same external diameter are released from the same height at the same time on an inclined plane. Both roll down without slipping. Which one will reach the bottom first?2010 · MCQ