A solid sphere rolls down on an inclined plane of inclination \(\theta\). What is the acceleration as the sphere reaches bottom?
1. \(\frac{5}{7}g\sin\theta\)
2. \(\frac{3}{5}g\sin\theta\)
3. \(\frac{2}{7}g\sin\theta\)
4. \(\frac{2}{5}g\sin\theta\)

Subtopic:  Moment of Inertia |
 79%
Level 2: 60%+
PMT - 2014
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Given below are two statements: 

Assertion (A): The speed of whirlwind in a tornado is alarmingly high.
Reason (R): If no external torque acts on a body, its angular velocity remains conserved.
 
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:  Angular Momentum |
Level 3: 35%-60%
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A solid cylinder of mass 'M' is suspended by two strings wrapped around it as shown. The acceleration 'a' and the tension T when the cylinder falls and the string unwinds itself are, respectively,
             
1. \(a=g,~T=\dfrac{Mg}{2}\)
2. \(a=\dfrac{g}{2},~T=\dfrac{Mg}{2}\)
3. \(a=\dfrac{g}{3},~T=\dfrac{Mg}{3}\)
4. \(a=\dfrac{2g}{3},~T=\dfrac{Mg}{6}\)

Level 3: 35%-60%
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An automobile engine develops 100 kW when rotating at a speed of 1800 rev/min. What torque does it deliver ?

1. 350 N-m

2. 440 N-m

3. 531 N-m

4. 628 N-m

Subtopic:  Torque |
 70%
Level 2: 60%+
PMT - 2000
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A bob of mass m attached to an inextensible string of length l is suspended from vertical support.  The bob rotates in a horizontal circle with an angular speed ω rad/s about the vertical.  About the point of suspension.

1.  Angular momentum is conserved
2. Angular momentum changes in magnitude but not in the direction
3. Angular momentum changes in direction but not in magnitude
4. Angular momentum changes both in direction and magnitude 

Subtopic:  Angular Momentum |
Level 3: 35%-60%
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A wheel is at rest. Its angular velocity increases uniformly and becomes 80 rad/s after 5 s. The total angular displacement is 

1. 800 rad

2. 400 rad

3. 200 rad

4. 100 rad

Subtopic:  Rotational Motion: Kinematics |
 71%
Level 2: 60%+
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A constant torque acting on a uniform circular wheel changes its angular momentum from \(A_0\) to \(4A_0\) in \(4~\text{s}\). The magnitude of this torque is:
1. \(\dfrac{3A_0}{4}\)
2. \(4A_0\)
3. \(A_0\)
4. \(12A_0\)

Subtopic:  Angular Momentum |
 88%
Level 1: 80%+
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A body rolls down an inclined plane without slipping. The fraction of total energy associated with its rotation will be

1.K2+R2
2.K2R2
3.K2K2+R2
4.R2K2+R2

Where k is radius of gyration of the body about an axis passing through centre of mass and R is the radius of the body. 

 74%
Level 2: 60%+
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A solid cylinder rolls down an inclined plane that has friction sufficient to prevent sliding. The ratio of rotational energy to total kinetic energy is

1.  12

2.  13

3.  23

4.  34

 

 70%
Level 2: 60%+
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A swimmer while jumping into water from a height easily forms a loop in the air, if

1. He pulls his arms and legs in
2. He spreads his arms and legs
3. He keeps himself straight
4. None of the above
Subtopic:  Moment of Inertia |
 78%
Level 2: 60%+
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