NEET Rotational Motion PYQ practice sheet

13 previous-year NEET Physics questions from Rotational Motion, newest papers first. Rotational Motion carries 15 of the Physics questions in NEET 2020 to 2026, so this is a good place to test yourself after revising the chapter. Marking: +4 correct, −1 wrong.

1. 1.

   RE-NEET 2026

   A solid sphere $A$ of radius $R$ and mass $M$ is attached at a point to a smaller solid sphere $B$ of radius $r < R$ and mass $m < M$. Assume that the line joining their centres lies along the horizontal. The moment of inertia of the system calculated about a vertical axis passing through the centre of $A$ is $I_A$ and that calculated about a vertical axis passing through the centre of $B$ is $I_B$. The difference $I_A - I_B$ is: Figure: the two touching spheres, drawn twice; on the left the vertical axis passes through the centre of $A$ (giving $I_A$) and on the right through the centre of $B$ (giving $I_B$). The centres are a distance $R + r$ apart.

   • (A)
     $(m - M)(R - r)^2$
   • (B)
     $(M - m)(R + r)^2$
   • (C)
     $0$
   • (D)
     $(m - M)(R + r)^2$
2. 2.

   RE-NEET 2026

   A thin horizontal disc is rotating about a vertical axis passing through its fixed centre $O$. Its angular momentum is $L_A$ and $L_B$ computed about points $A$ and $B$, respectively, with $OB = 2 \times OA$. The value of $\frac{L_A}{L_B}$ is: Figure: a disc rotating about a vertical axis through its centre $O$. Points $A$ and $B$ lie on a horizontal line from $O$, with $A$ at distance $OA$ and $B$ at distance $OB = 2\,OA$.

   • (A)
     $1$
   • (B)
     $\frac{1}{4}$
   • (C)
     $2$
   • (D)
     $\frac{1}{2}$
3. 3.

   NEET 2026

   The angular speed of a flywheel is increased from 600 rpm to 1200 rpm in 10 s. The number of revolutions completed by the flywheel during this time is:

   • (A)
     900
   • (B)
     150
   • (C)
     600
   • (D)
     300
4. 4.

   NEET 2026

   A thin wire of length '$L$' and linear mass density '$m$' is bent into a circular ring (in $x$-$y$ plane) with centre '$C$' as shown in figure. The moment of inertia of the ring about an axis $yy'$ will be: The axis $yy'$ lies in the plane of the ring and touches it at one point (it is a tangent to the ring).

   • (A)
     $\dfrac{3mL^3}{8\pi^2}$
   • (B)
     $\dfrac{3mL^2}{8\pi}$
   • (C)
     $\dfrac{3mL^2}{8\pi^2}$
   • (D)
     $\dfrac{3mL^3}{8\pi}$
5. 5.

   NEET 2024

   The moment of inertia of a thin rod about an axis passing through its mid point and perpendicular to the rod, is $2400\ \text{g cm}^2$. The length of the 400 g rod is nearly:

   • (A)
     8.5 cm
   • (B)
     17.5 cm
   • (C)
     72.0 cm
   • (D)
     20.7 cm
6. 6.

   NEET 2024

   A wheel of a bullock cart is rolling on a level road as shown in the figure below. If its linear speed is $v$ in the direction shown, which one of the following options is correct ($P$ and $Q$ are any highest and lowest points on the wheel respectively)?

   • (A)
     Point $P$ moves faster than point $Q$.
   • (B)
     Both the points $P$ and $Q$ move with equal speed.
   • (C)
     Point $P$ moves slower than point $Q$.
   • (D)
     Point $P$ has zero speed.
7. 7.

   NEET 2023

   The ratio of radius of gyration of a solid sphere of mass $M$ and radius $R$ about its own axis to the radius of gyration of the thin hollow sphere of same mass and radius about its axis is :

   • (A)
     5 : 2
   • (B)
     3 : 5
   • (C)
     5 : 3
   • (D)
     2 : 5
8. 8.

   NEET 2023

   The angular acceleration of a body, moving along the circumference of a circle, is :

   • (A)
     along the axis of rotation
   • (B)
     along the radius, away from centre
   • (C)
     along the radius towards the centre
   • (D)
     along the tangent to its position
9. 9.

   NEET 2022

   The ratio of the radius of gyration of a thin uniform disc about an axis passing through its centre and normal to its plane, to the radius of gyration of the disc about its diameter is:

   • (A)
     $1:\sqrt2$
   • (B)
     $2:1$
   • (C)
     $\sqrt2:1$
   • (D)
     $4:1$
10. 10.

    NEET 2022

    The angular speed of a fly wheel moving with uniform angular acceleration changes from 1200 rpm to 3120 rpm in 16 seconds. The angular acceleration in $\text{rad/s}^2$ is:

    • (A)
      $104\pi$
    • (B)
      $2\pi$
    • (C)
      $4\pi$
    • (D)
      $12\pi$
11. 11.

    NEET 2021

    From a circular ring of mass $M$ and radius $R$ an arc corresponding to a $90^\circ$ sector is removed. The moment of inertia of the remaining part of the ring about an axis passing through the centre of the ring and perpendicular to the plane of the ring is $K$ times $MR^{2}$. Then the value of $K$ is :

    • (A)
      $\dfrac{7}{8}$
    • (B)
      $\dfrac{1}{4}$
    • (C)
      $\dfrac{3}{4}$
    • (D)
      $\dfrac{1}{8}$
12. 12.

    NEET 2021

    A uniform rod of length $200\ \mathrm{cm}$ and mass $500\ \mathrm{g}$ is balanced on a wedge placed at $40\ \mathrm{cm}$ mark. A mass of $2\ \mathrm{kg}$ is suspended from the rod at $20\ \mathrm{cm}$ and another unknown mass $m$ is suspended from the rod at $160\ \mathrm{cm}$ mark as shown in the figure. Find the value of $m$ such that the rod is in equilibrium. ($g = 10\ \mathrm{m/s^2}$) Figure: a horizontal rod marked from 0 to 200 cm, supported on a wedge at the 40 cm mark, with a $2\ \mathrm{kg}$ mass hanging at the 20 cm mark and the mass $m$ hanging at the 160 cm mark.

    • (A)
      $\dfrac{1}{2}\ \mathrm{kg}$
    • (B)
      $\dfrac{1}{12}\ \mathrm{kg}$
    • (C)
      $\dfrac{1}{6}\ \mathrm{kg}$
    • (D)
      $\dfrac{1}{3}\ \mathrm{kg}$
13. 13.

    NEET 2020

    Find the torque about the origin when a force of $3\hat{j}$ N acts on a particle whose position vector is $2\hat{k}$ m.

    • (A)
      $6\hat{i}$ N m
    • (B)
      $6\hat{j}$ N m
    • (C)
      $-6\hat{i}$ N m
    • (D)
      $6\hat{k}$ N m