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%+
Hints

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:
1. \(1:\sqrt{2}\) 2. \(2:1\)
3. \(\sqrt{2}:1\) 4. \(4:1\)
Subtopic:  Moment of Inertia |
 68%
Level 2: 60%+
NEET - 2022
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%
Hints

advertisementadvertisement

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 |
 80%
Level 1: 80%+
Hints

The ratio of the moments of inertia of two spheres, about their diameters, having the same mass and their radii being in the ratio of \(1:2\), is:

1. \(2:1\) 2. \(4:1\)
3. \(1:2\) 4. \(1:4\)
Subtopic:  Moment of Inertia |
 82%
Level 1: 80%+
NEET - 2022
Hints

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
Hints

advertisementadvertisement

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%+
Hints

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%+
Hints

advertisementadvertisement

What is the value of linear velocity, if the angular velocity vector is  \(\vec{\omega}=3 \hat{i}-4 \hat{j}+\hat{k}\) and the position vector is \(\vec {r}=5 \hat{i}-6 \hat{j}+6 \hat{k}?\) 
1. \(-18 \hat{i}-13 \hat{j}+2 \hat{k}\)
2. \(18 \hat{i}+13 \hat{j}-2 \hat{k}\)
3. \(6 \hat{i}+2 \hat{j}-3 \hat{k}\)
4. \(6 \hat{i}-2 \hat{j}+8 \hat{k}\)
Subtopic:  Rotational Motion: Kinematics |
 75%
Level 2: 60%+
Hints