For a body, with angular velocity \( \vec{\omega }=\hat{i}-2\hat{j}+3\hat{k}\)  and radius vector \( \vec{r }=\hat{i}+\hat{j}++\hat{k},\)  its velocity will be:
1. \(-5\hat{i}+2\hat{j}+3\hat{k}\)
2. \(-5\hat{i}+2\hat{j}-3\hat{k}\)
3. \(-5\hat{i}-2\hat{j}+3\hat{k}\)
4. \(-5\hat{i}-2\hat{j}-3\hat{k}\)

Subtopic:  Rotational Motion: Kinematics |
 68%
From NCERT
AIPMT - 1999
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A uniform rod of length \(200~ \text {cm}\) and mass \(500~ \text g\) is balanced on a wedge placed at \(40~ \text{cm}\) mark. A mass of \(2~\text{kg}\) is suspended from the rod at \(20~ \text{cm}\) and another unknown mass \( \text m\) is suspended from the rod at \(160~\text{cm}\) mark as shown in the figure. What would be the value of \( \mathrm{m}\) such that the rod is in equilibrium? (Take \(g=10~( \text {m/s}^2)\)

         

1. \({1 \over 6}~ \text{kg}\) 2. \({1 \over 12}~ \text{kg}\)
3. \({1 \over 2}~ \text{kg}\) 4.  \({1 \over 3}~ \text{kg}\)
Subtopic:  Torque |
 55%
From NCERT
NEET - 2021
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Consider two uniform discs of the same thickness and different radii \(R_1=R\) and \(R_2=\alpha R\)  made of the same material. If the ratio of their moments of inertia, \(I_1\) and\(I_2,\) respectively, about their axes is \(I_1:I_2=1:16,\)then the value of \(\alpha\) is:
1. \(\sqrt{2}\)
2. \(4\)
3. \(2\)
4. \(2\sqrt{2}\)

Subtopic:  Moment of Inertia |
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A body is in pure rotation. The linear speed \(v\) of a particle, the distance \(r\) of the particle from the axis and the angular velocity \(\omega\) of the body are related as \(w=\dfrac{v}{r}\). Thus:
1. \(w\propto\dfrac{1}{r}\)
2. \(w\propto\ r\)
3. \(w=0\)
4. \(w\) is independent of \(r\)

Subtopic:  Rotational Motion: Kinematics |
 61%
From NCERT
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If there is no external force acting on a non-rigid body which of the following quantities must remain constant?

a. angular momentum
b. linear momentum
c. kinetic energy
d. moment of inertia
Choose the correct option:
1. (a) and (b)
2. (b) and (c)
3. (c) and (d)
4. (a) and (d)

Subtopic:  Angular Momentum |
 52%
From NCERT
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A uniform rod of mass \(m\) and length \(L\) is struck at both ends by two particles of masses m, each moving with identical speeds \(u,\) but in opposite directions, perpendicular to its length. The particles stick to the rod after colliding with it. The system rotates with an angular speed:
        
1. \(\frac{u}{L}\)

2. \(\frac{2u}{L}\)

3. \(\frac{12u}{7L}\)

4. \(\frac{6u}{L}\)

Subtopic:  Angular Momentum |
 55%
From NCERT
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The following are the given statements:
a. for a general rotational motion, angular momentum \(L\) and angular velocity \(\omega\) need not be parallel.
b. for a rotational motion about a fixed axis, angular momentum \(L\) and angular velocity \(\omega\) are always parallel.
c. for a general translational motion, momentum \(p\) and velocity \(v\) are always parallel.
d. for a general translational motion, acceleration \(a\) and velocity \(v\) are always parallel.
Choose the correct option:
1. (a), (c)
2. (b), (c)
3. (c), (d)
4. (a), (b), (c)
Subtopic:  Angular Momentum |
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Which of the following points is the likely position of the center of mass of the system shown in the figure?

 

1. \(A\)
2. \(B\)
3. \(C\)
4. \(D\)

Subtopic:  Center of Mass |
 74%
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A block \(A\) is pushed on a smooth horizontal plane by applying a horizontal force \(F ,\) which causes an acceleration of \({g \over 4}\) (\(g\): acceleration due to gravity). The block does not topple, even though the force acts at its highest point. The normal reaction shifts forward by:
               
1. \({ b\over 2}\)
2. \({ b\over 4}\) 
3. \({ b\over 8}\)
4. \(b\over 3\)
Subtopic:  Torque |
From NCERT
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A uniform disc of mass \(m\) and radius \(r\) is rotating freely about its own axis, which is kept vertical. There is a small insect of mass \(\frac m2\) sitting on the periphery of the disc, also rotating with the disc. The initial angular speed of the disc is \(\omega_0.\) The insect moves radially inward and finally reaches the centre. The final angular speed of the disc is:
1. \(\omega_0\)
2. \(2\omega_0\)
3. \(\frac32\omega_0\)
4. \(\frac52\omega_0\)
Subtopic:  Angular Momentum |
 61%
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