# Practice Test: Question Set - 01

**1. ‘A’ and ‘B’ are two solid cylinders made of aluminum. Their dimensions are shown. The ratio of the rotational inertia of B to that of ‘A’ about the common axis X-X' is:**

- (A) 2

- (B) 4

- (C) 8

- (D) 32

**2. A disk starts from rest and rotates about a fixed axis, subject to a constant net torque. The work done by the torque during the second revolution is _________ as the work done during the first revolution.**

- (A) The
same

- (B) Twice
as much

- (C) Half
as much

- (D) Four
times as much

**3. A wheel rotates with a constant angular acceleration of Ï€ rad/s². During the time interval from**

*t*to_{1}*t*its angular displacement is Ï€ rad. At time_{2}*t*its angular velocity is 2Ï€ rad/sec. Its angular velocity in rad/s at time_{2}*t*is:_{1}- (A) Zero

- (B) 1

- (C)

*Ï€*

- (D)

*Ï€*/√2

**4. A wheel initially has an angular velocity of -36 rad/sec but after 6.0 sec its angular velocity is -24 rad/sec. If its angular acceleration is constant the value is:**

- (A) 2.0 rad/sec

^{2}

- (B) -2.0 rad/sec

^{2}

- (C) 3.0 rad/sec

^{2}

- (D) -3.0 rad/sec

^{2}

**5. A child, riding on a large merry-go-round, travels a distance of 3000 m in a circle of diameter 40 m. The total angle in radians through which she revolves is:**

- (A) 50

- (B) 75

- (C) 150

- (D) None
of these

**6. For a wheel spinning on an axis through its center, the ratio of the tangential acceleration of a point on the rim to the tangential acceleration of a point halfway between the center and the rim is:**

- (A) 1

- (B) 2

- (C) 1/2

- (D) 4

**7. Three identical balls are tied by light strings to the same rod and rotate around it, as shown below. Rank the balls according to their rotational inertia, least to greatest.**

- (A) 1, 2, 3

- (B) 3, 2, 1

- (C) 3, then 1
and 2 tie

- (D) 1, 3, 2

**8. The rotational inertia of a disk about its axis is 0.70 kg.m**

^{2}. When a 2.0 kg weight is added to its rim, 0.40 m from the axis, the rotational inertia becomes:- (A) 0.38 kg.m

^{2}

- (B) 0.54 kg.m

^{2}

- (C) 0.70 kg.m

^{2}

- (D) 1.0 kg.m

^{2}

**9. One revolution is about the same as:**

- (A) 1
rad

- (B) 57 rad

- (C)

*Ï€*/2 rad

- (D) 2

*Ï€*rad

**10. A disk with a rotational inertia of 5.0 kg.m**

^{2}and a radius of 0.25 m rotates on a frictionless fixed axis perpendicular to the disk and through its center. A force of 8.0 N is applied tangentially to the rim. The angular acceleration of the disk is:- (A) 0.40 rad/s

^{2}

- (B) 0.4 rad/s

^{2}

- (C) 1.0 rad/s

^{2}

- (D) 2.5 rad/s

^{2}

**11. A 16 kg block is attached to a cord that is wrapped around the rim of a flywheel of diameter 0.40 m and hangs vertically, as shown. The rotational inertia of the flywheel is 0.50 kgm**

^{2}. When the block is released and the cord unwinds, the acceleration of the block is:- (A) 0.15

*g*

- (B) 0.56

*g*

- (C) 0.84

*g*

- (D) 100

*g*

**12. A 8.0-cm radius disk with a rotational inertia of 0.12 kgm**

^{2}is free to rotate on a horizontal axis. A string is fastened to the surface of the disk and a 10-kg mass hangs from the other end. The mass is raised by using a crank to apply a 9.0-Nm torque to the disk. The acceleration of the mass is:- (A) 0.50 m/s

^{2}

- (B) 1.7 m/s

^{2}

- (C) 6.2 m/s

^{2}

- (D) 12 m/s

^{2}

**13. A pulley with a radius of 3.0 cm and a rotational inertia of 4.5 × 10**

^{-3}kgm^{2}is suspended from the ceiling. A rope passes over it with a 2.0-kg block attached to one end and a 4.0-kg block attached to the other. The rope does not slip on the pulley. At any instant after the blocks start moving the object with the greatest kinetic energy is:- (A) The
heavier block

- (B) The
lighter block

- (C) The
pulley

- (D) Either block
(the two blocks have the same kinetic energy)

**14. If a wheel turns with constant angular speed then:**

- (A) Each
point on its rim moves with constant velocity

- (B) Each
point on its rim moves with constant acceleration

- (C) The
wheel turns through equal angles in equal times

- (D) The
angle through which the wheel turns in each second increases as time goes on

**15. A flywheel, initially at rest, has a constant angular acceleration. After 9 s the flywheel has rotated 450 rad. Its angular acceleration in rad/sec**

^{2}is:- (A) 100

- (B) 1.77

- (C) 50

- (D) 11.1

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