A uniform rod on a smooth horizontal table is moving with uniform horizontal speed \(v.\) Suddenly rod is hinged at the centre of the rod. The angular velocity of the rod, now, will be:
1. \(\dfrac{2v}{3l}\) 2. \(\dfrac{3v}{2l}\)
3. \(\dfrac{v}{l}\) 4. zero

Subtopic:  Angular Momentum |
 61%
Level 2: 60%+
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A solid sphere of mass \(m\) is in pure rolling motion with the centre of mass moving with velocity \(v_{0}.\) It's angular momentum about the point \(P\) shown in the diagram is:
1. \(\dfrac{2}{5}mv_{0}R\) 2. \(\dfrac{1}{5}mv_{0}R\)
3. \(\dfrac{7}{5}mv_{0}R\) 4. \(mv_{0}R\)
 
Subtopic:  Angular Momentum |
 75%
Level 2: 60%+
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The body of mass \(1.5~\text{kg}\) rotating about an axis with angular velocity of \(0.3~\text{rad s}^{-1}\) has the angular momentum of \(1.8~\text{kg m}^2\text{s}^{-1}\). The radius of gyration of the body about the axis is:
1. \(2~\text{m}\)
2. \(1.2~\text{m}\)
3. \(0.2~\text{m}\)
4. \(1.6~\text{m}\)
Subtopic:  Angular Momentum |
 86%
Level 1: 80%+
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A uniform rod of mass \(m\) and length \(l\) is in uniform translational motion. If one of its ends is suddenly hinged, then (hinge is smooth):
1. It will continue its translational motion.
2. It will now be in pure rotational motion about the hinged end.
3. It will now have combined translational and rotational motion.
4. It will stop.
Subtopic:  Angular Momentum |
 72%
Level 2: 60%+
Hints

Given below are two statements: 
Assertion (A): If there is no external torque on a body about its centre of mass, then the velocity of the centre of mass remains constant.
Reason (R): The linear momentum of an isolated system remains constant.
 
1. Both (A) and (R) are True and (R) is the correct explanation of (A).
2. Both (A) and (R) are True but (R) is not the correct explanation of (A).
3. (A) is True but (R) is False.
4. (A) is False but (R) is True.
Subtopic:  Torque |
Level 3: 35%-60%
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Given below are two statements: 
Assertion (A): If the ice on the polar caps of the earth melts, then the length of the day will increase.
Reason (R): Moment of inertia of the earth increases, as ice on polar caps melts.
 
1. Both (A) and (R) are True and (R) is the correct explanation of (A).
2. Both (A) and (R) are True but (R) is not the correct explanation of (A).
3. (A) is True but (R) is False.
4. (A) is False but (R) is True.
Subtopic:  Angular Momentum |
 79%
Level 2: 60%+
Hints

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A string is wrapped along the rim of a wheel of the moment of inertia \(0.10~\text{kg-m}^2\) and radius \(10~\text{cm}.\) If the string is now pulled by a force of \(10~\text N,\) then the wheel starts to rotate about its axis from rest. The angular velocity of the wheel after \(2~\text s\) will be:

1. \(40~\text{rad/s}\) 2. \(80~\text{rad/s}\)
3. \(10~\text{rad/s}\) 4. \(20~\text{rad/s}\)
Subtopic:  Rotational Motion: Dynamics |
 80%
Level 1: 80%+
NEET - 2022
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Given below are two statements: 
Assertion (A): For a body under translatory as well as rotational equilibrium, net torque about any axis is zero.
Reason (R): Together \( \Sigma \vec{F}_{i}=0 \text { and } \Sigma\left(\vec{r}_{i} \times \vec{F}_{i}\right)=0 \) implies that \( \Sigma\left(\vec{r}_{i}-\overrightarrow{r_{0}}\right) \times \vec{F}=0 \).
  
1. Both (A) and (R) are True and (R) is the correct explanation of (A).
2. Both (A) and (R) are True but (R) is not the correct explanation of (A).
3. (A) is True but (R) is False.
4. Both (A) and (R) are False.
Subtopic:  Rotational Motion: Dynamics |
 75%
Level 2: 60%+
Hints

Given below are two statements: 
Assertion (A): The axis of rotation of a rigid body cannot lie outside the body.
Reason (R): It must pass through a material particle of the body.
  
1. Both (A) and (R) are True and (R) is the correct explanation of (A).
2. Both (A) and (R) are True but (R) is not the correct explanation of (A).
3. (A) is True but (R) is False.
4. Both (A) and (R) are False.

Subtopic:  Rotational Motion: Kinematics |
 72%
Level 2: 60%+
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A ring of mass of \(10~\text{kg}\) and diameter of \(0.4~\text m\) is rotated about its axis. If it makes \(2100\) revolutions per minute, then its angular momentum will be:
1. \(44~\text{kg m}^{2} \text{s}^{-1}\)
2. \(88 ~\text{kg m}^{2} \text{s}^{-1}\)
3. \(4.4~\text{kg m}^{2} \text{s}^{-1}\)
4. \(0.4~\text{kg m}^{2} \text{s}^{-1}\)
Subtopic:  Angular Momentum |
 81%
Level 1: 80%+
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