A man stands on a rotating platform, with his arms stretched horizontally holding a 5 kg weight in each hand. The angular speed of the platform is 30 revolutions per minute. The man then brings his arms close to his body with the distance of each weight from the axis changing from 90 cm to 20 cm. The moment of inertia of the man together with the platform may be taken to be constant and equal to 7.6 kg m2. What is his new angular speed?

1. 60 rev/min
2. 57.0 rev/min
3. 58.8 rev/min
4. 60.1 rev/min

Subtopic:  Angular Momentum |
 51%
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NEET 2023 - Target Batch - Aryan Raj Singh
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A bullet of mass \(10\) g and speed \(500\) m/s is fired into a door and gets embedded exactly at the center of the door. The door is \(1.0\) m wide and weighs \(12\) kg. It is hinged at one end and rotates about a vertical axis practically without friction. The angular speed of the door just after the bullet embeds into it is:
1. \(0.122\) rad/s
2. \(0.625\) rad/s
3. \(0.231\) rad/s
4. \(0.191\) rad/s

Subtopic:  Angular Momentum |
 62%
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NEET 2023 - Target Batch - Aryan Raj Singh
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A disc rotating about its axis with angular speed ω0 is placed lightly (without any translational push) on a perfectly frictionless table. The radius of the disc is R. The linear velocities of the points A, B, and C on the disc (as shown in the figure) respectively are:
     
1. \(\omega_0 R, \omega_0 R, \frac{\omega_0 R}{2}\)
2. \(\frac{\omega_0 R}{2}, \omega_0 R, \omega_0 R\)
3. \(\omega_0 \mathrm{R}, \frac{\omega_0 \mathrm{R}}{2}, \omega_0 \mathrm{R}\)
4. \(\omega_0 R, \omega_0 R, 0\)

Subtopic:  Rolling Motion (OLD NCERT) |
 57%
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NEET 2023 - Target Batch - Aryan Raj Singh
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A cylinder of mass \(10\) kg and radius of \(15\) cm is rolling perfectly on a plane of inclination \(30^\circ.\) The coefficient of static friction \(\mu_s=0.25.\) How much is the force of friction acting on the cylinder?
1. \(16.3\) N
2. \(15.5\) N
3. \(19.1\) N
4. \(20.0\) N

Subtopic:  Rolling Motion (OLD NCERT) |
 52%
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NEET 2023 - Target Batch - Aryan Raj Singh
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Three point masses m1, m2 and m3 are placed at the corners of a thin massless rectangular sheet (1.2 m x 1.0 m) as shown. Centre of mass will be located at the point

(1) (0.8, 0.6) m

(2) (0.6, 0.8) m

(3) (0.4, 0.4) m

(4) (0.5, 0.6) m

Subtopic:  Center of Mass |
 73%
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NEET 2023 - Target Batch - Aryan Raj Singh
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Figure shows a composite system of two uniform rods of lengths as indicated. Then the coordinates of the centre of mass of the system of rods are

(1) L2,2L3

(2) L4,2L3

(3) L6,2L3

(4) L6,L3

Subtopic:  Center of Mass |
 64%
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A man of mass m starts moving on a plank of mass M with constant velocity v with respect to plank. If the plank lles on a smooth horizontal surface, then velocity of plank with respect to ground is

(1) Mvm+M

(2) mvM

(3) Mvm

(4) mvm+M

 63%
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A ball of mass m is thrown upward and another ball of same mass is thrown downward so as to move freely under gravity. The acceleration of centre of mass is

(1) g

(2) g2

(3) 2g

(4) Zero

Subtopic:  Center of Mass |
 63%
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A hollow sphere of mass 1 kg and radius 10 cm is free to rotate about its diameter. If a force of 30 N is applied tangentially to it, its angular acceleration is (in rad/s2)

(1) 5000

(2) 450

(3) 50

(4) 5

Subtopic:  Torque |
 84%
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Two equal and opposite forces are applied tangentially to a uniform disc of mass M and radius R as shown in the figure. If the disc is pivoted at its centre and free to rotate in its plane, the angular acceleration of the disc is

(1) FMR

(2) 2F3MR

(3) 4FMR

(4) Zero

Subtopic:  Torque |
 62%
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