(a) If both assertion and reason are true and reason is the correct explanation of the assertion.
(b) If both assertion and reason are true but reason is not correct explanation of the assertion.
(c) If assertion is true, but reason is false.
(d) If both assertion and reason are false.
(e) If reason is true but assertion is false.
Assertion: A hollow shaft is found to be stronger than a solid shaft made of same material.
Reason: The torque required to produce a given twist in hollow cylinder is greater than that required to twist a solid cylinder of same size and material
70%
(a)
10%
(b)
20%
(c)
0%
(d)
0%
(e)
Q.2.
A solid cylinder of mass M and radius R is being pulled along a horizontal surface on which its perform pure rolling by a horizontal force F applied at its center. Which of the following is true?
(more than one correct)
58%
Angular acceleration of the cylinder about the axis passing through center of mass is 2F/3MR
8%
Frictional force acting on the cylinder is F/3correct
33%
Velocity of a point on the top of cylinder after 3 sec is 4P/Mcorrect
0%
None of these
Q.3.
Three points masses each of mass m are placed at the corner of an equilateral triangle of side a.The moment of inertia of the system about an axis along one side of an triangle is
50%
3ma2/4
25%
ma2/4
17%
ma2/2
8%
ma2/6
Q.4.
A circular disc X of radius R is made from an iron pole of thickness t, and another disc Y of radius 4R is made from an iron plate of thickness t/then the relation between the moment of inertia $I_x$ and $I_y$ is
42%
$I_y=32I_x$
17%
$I_y=16I_x$
42%
$I_y=64I_x$
0%
$I_y=2I_x$
Q.5.
Three masses are placed on the x-axis: 300 g at origin,500 g at x = 40 cm and 400 g at x = 70 cm. The distance of the centre of mass from the origin
31%
40 cm
25%
45 cm
44%
50 cm
0%
30 cm
Q.6.
A solid cylinder, a circular disc, a solid sphere and a hollow cylinder of the same radius are placed on an inclined plane. Which of the following will have maximum acceleration at the bottom of the plane?
0%
Circular disc
45%
Solid cylinder
55%
Solid sphere
0%
Hollow cylinder
Q.7.
Two discs of moments of inertia I1 and I2 about their respective axis rotating with angular frequencies ω1 and ω2 respectively are brought into contact face to face with their axes of rotation coincident. Which of the following is true?
(more than one correct)
50%
The angular frequency of the composite disc is (I1ω1+I2ω2)/(I1+I2)
40%
dL/dt is constant for the systemcorrect
0%
Moment of the inertia of the composite disc about the axis is I1+I2correct
10%
None of these
Q.8.
For which of the following does the centre of mass lie outside the body?
10%
A pencil
40%
A shotput
30%
A dice
20%
A bangle
Q.9.
The direction of the angular velocity vector is along
60%
the tangent to the circular path
10%
the inward radius
20%
the outward radius
10%
the axis of rotation
Q.10.
A drum of radius R and mass M, rolls down without slipping along an inclined plane of angle $\theta$. The frictional force
33%
dissipates energy as heat
11%
decreases the rotational motion
44%
decreases the rotational and translational motion
11%
converts translational energy to rotational energy
Q.11.
The speed of a homogeneous solid sphere after rolling down an inclined plane of vertical height h, from rest, without sliding is
0%
$\sqrt {gh}$
25%
$\sqrt {(6/5)gh}$
50%
$\sqrt {(4/3)gh}$
25%
$\sqrt {(10/7)gh}$
Q.12.
A solid sphere rolls without slipping with speed v and presses a spring of spring constant k.The compression in the spring will be
11%
(2Mv2/3k)1/2
44%
(2Mv2/5k)1/2
33%
(5kv2/7M)1/2
11%
(7Mv2/5k)1/2
Q.13.
When a mass is rotating in a plane about a fixed point, its angular momentum is directed along
38%
a line perpendicular to the plane of rotation
38%
the line making an angle of 45° to the plane of rotation
12%
the radius
12%
the tangent to the orbit
Q.14.
A particle of mass m is rotating in a plane in circular path of radius R. Its angular momentum is L. The centripetal force acting on the particle is
25%
$\frac {L^2}{mR}$
38%
$\frac {L^2m}{R}$
12%
$\frac {L^2}{m^2R^2}$
25%
$\frac {L^2}{mR^2}$
Q.15.
The motion of center of mass of a system of two particles is unaffected by their internal forces
25%
irrespective of the actual direction of the internal forces
12%
only if they are along the line joining the particles
38%
Only if they are obliquely inclined to the line joining the particles
25%
only if they are right angles to the line joining the particles
Q.16.
A Merry-go-round, made of a ring-like platform of radius R and mass M, is revolving with angular speed $\omega$ . A person of mass M is
standing on it. At one instant, the person jumps off the round, radially away from the centre of the round (as seen from the round).
The speed of the round afterwards is
43%
$\omega$
29%
$2\omega$
29%
$\omega/2$
0%
0
Q.17.
(a) If both assertion and reason are true and reason is the correct explanation of the assertion.
(b) If both assertion and reason are true but reason is not correct explanation of the assertion.
(c) If assertion is true, but reason is false.
(d) If both assertion and reason are false.
(e) If reason is true but assertion is false.
Assertion: Centre of mass of a system does not move under the action of internal forces.
Reason: Internal forces are non conservative forces.
67%
(a)
0%
(b)
0%
(c)
17%
(d)
17%
(e)
Q.18.
Net force on a system of particles is zero from some interial frame. Which of the following is correct?
(more than one correct)
14%
Center of mass acceleration is zero from that inertial frame
29%
Net momentum is constant from that framecorrect
43%
Net momentum from the frame of Center of mass is zero and constantcorrect
14%
KE of the system from center of mass frame may be constantcorrect
Q.19.
The net external torque on a system of particles about an axis is zero. Which of the following are compatible with it ?
(more than one correct)
14%
The forces may be acting radially from a point on the axis
43%
The forces may be acting on the axis of rotationcorrect
14%
The forces may be acting parallel to the axis of rotationcorrect
29%
The torque caused by some forces may be equal and opposite
to that caused by other forces.correct
Q.20.
The moment of inertia of a rigid body, depends upon
50%
distribution of mass from axis of rotation.
12%
angular velocity of the body.
25%
angular acceleration of the body.
12%
mass of the body.
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