Q.1
Three identical spheres, each of mass 1 kg are kept as shown in figure, touching each other, with their centre on a straight line. If their centre are marked P,Q,R respectively, the distance of centre of mass of the system from P is [ kerala C.E.T 2005]
ch-6_que_no-118_img_no1.png
  • a) (PQ + PR + QR) / 3
  • b) (PQ + PR) / 3
  • c)(PQ + QR) / 3
  • d)(PQ + QR + PR) / 3
Q.2
A solid cylinder of mass 20kg has length 1m and radius 0.2m. Then its moment of inertia in kgm2 about its geometrical axis is [ kerala PMT 2005]
  • a)0.8
  • b) 0.4
  • c)0.2
  • d)20.4
Q.3
A given shaped glass tube having uniform cross section is filed with water and is mounted on a rotating shaft as shown in figure. If the tube is rotated with constant angular velocity ω, then [ AIIMS 2005]
ch-6_que_no-120_img_no1.png
  • a) water levels in both section A and B goes up
  • b) water level in section A goes up and then in section B comes down
  • c) Water level in section A comes down and then in B goes up
  • d) water level remains the same in both the sections
Q.4
A constant torque is acting on a uniform circular wheel changes its angular momentum from A0 to 4A0 in 4 seconds. The magnitude of this torque is [ BHU 1998]
  • a)(3/4)A0
  • b) A0
  • c)4A0
  • d)12A0
Q.5
An inclined plane makes an angle of 30° with the horizontal. A solid sphere rolling down this inclined plane from rest without slipping has a linear acceleration equal to [ MPPMT 1987]
  • a) g/3
  • b) 2g/3
  • c)5g/7
  • d)5g/14
Q.6
The moment of inertia of a circular ring about an axis passing through its centre and normal to its plane passing through its centre and normal to its plane is 200gm/cmThen its moment of inertia about a diameter is [ MPPMT 1987]
  • a) 40 gm cm2
  • b) 300 gm cm2
  • c)200 gm cm2
  • d)100 gm cm2
Q.7
Moment of momentum is called
  • a) torque
  • b) weight
  • ac) moment of inertia
  • d) angular momentum
Q.8
A dancer on ice spins faster when she folds her hand. This is due to [ CPMT 1986]
  • a)increase in energy and increase in angular momentum
  • b) decrease in friction at the skates
  • c)constant angular momentum and increase in kinetic energy
  • d)increase in energy and decrease in angular momentum
Q.9
The rotational K.E. of a body is E and its moment of inertia id I. The angular momentum is [ MPPMT 1993]
  • a) EI
  • b) 2 √(EI)
  • c) √(2EI)
  • d)E/I
Q.10
A spherical solid ball of 1kg mass and radius 3cm is rotating about an axis passing through its centre with an angular velocity of 50 radian/sec. The kinetic energy of rotation is [ CPMT 1989]
  • a) 4500J
  • b) 90J
  • c) 9×10-3 J
  • d) (9/20) J
Q.11
The quantity which remains constant in conservative field if [ Raj.PET 1996]
  • a)Potential energy
  • b) Kinetic energy
  • c)Angular momentum
  • d)Linear momentum
Q.12
A body is moving with a constant velocity, then which of the following statement is correct :
  • a) the body necessarily a constant angular momentum
  • b) the body has necessarily a constant moment of inertia
  • c)the body has necessarily a constant angular speed and moment of inertia
  • d)the angular speed and moment of inertia may vary but their product is constant
Q.13
A meter stick is held vertically with one end on the floor and is then allowed to fall. The speed of the other end when it hits the floor assuming that the end at floor does not slip is [ g=9.8 m/s2] [ JIPMER 1998]
  • a) 3.2 m/s
  • b) 5.4 m/s
  • c) 7.6 m/s
  • d) 9.2 m/s
Q.14
A rod pQ of mass M and length L is hinged at one end O. The rod is kept in horizontal position by a massless string tied to point Q as shown in figure. When the string is cut the initial angular acceleration of the rod is
ch-6_que_no-132_img_no1.png
  • a) (g/L)
  • b) 2(g/L)
  • c) (2/3)(g/L)
  • d) (3/2)(g/L)
Q.15
Angular momentum of the body is conserved [ MPPET 1995]
  • a) Always
  • b) never
  • c) in presence of external torque
  • d) in absence of external torque
Q.16
You are given two circular disc which have equal weight and equal thickness. they are made up of different metals having densities d1 and dthere radii are R1 and R2 respectively. For disc that will have more moment of inertia about the central axis than the other, the condition is [ MPPET 1993]
  • a) d1 > d2
  • b) R1 > R2
  • c)d1> d2 and R1 > R2
  • d)d1 < d2 and R1 < R2
Q.17
If the moment of inertia of disc about the tangent in its plane is I, its moment of inertia about the tangent perpendicular to the plane will be [ Raj. PET 1996]
  • a)6I /5
  • b)3I/4
  • c)3I/2
  • d)5I/4
Q.18
The rotational and translation kinetic energy of rolling body are same, the body is [ RajPET 1996]
  • a) Disc
  • b) Sphere
  • c) Cylinder
  • d) Ring
Q.19
A body having moment of inertia about its axis of rotation equal to 3 kg m2 i rotating with angular velocity equal to 3rad/s. Kinetic energy of this rotating body is the same as that of body of mass 27kg moving with a speed of [ SCRA 1994]
  • a)1.0 ms2
  • b) 0.5 ms2
  • c)1.5 ms2
  • d)2.0 ms2
Q.20
A cord is wound round the circumference of wheel of radius r. The axis of the wheel is horizontal and moment of inertia about it is I. A weight mg is attached to the end of the cord and falls from rest. After falling through a distance h, the angular velocity of the wheel will be [ MPPMT 1994]
  • a)
    ch-6_qn-138choice_img_no1.png
  • b)
    ch-6_qn-138choice_img_no2.png
  • c)
    ch-6_qn-138choice_img_no3.png
  • d)
    ch-6_qn-138choice_img_no4.png
Q.21
A rigid body rotates about a fixed axis with variable angular velocity equal to ω=α - βt, at time t, α and β are constants. find the angle turned through by the body before coming to rest
  • a)
    ch-6_qn-139choice_img_no1.png
  • b)
    ch-6_qn-139choice_img_no2.png
  • c)
    ch-6_qn-139choice_img_no3.png
  • d)
    ch-6_qn-139choice_img_no4.png
Q.22
Before jumping in water from above a swimmer bends his body to [ MPPMT 1994]
  • a) increase moment of inertia
  • b) decrease moment of inertia
  • c) decrease the angular momentum
  • d) reduce the angular velocity
Q.23
A particle of mass m=5 is moving with a uniform speed v=3√2 in the XY plane along the straight line Y=X +The magnitude of the angular momentum about origin is
  • a)zero
  • b) 30 units
  • c)75 units
  • d)40√2 units
Q.24
A tap can be operated easily using two fingers because : [ UGET 1995]
  • a) the force available for the operation will be more
  • b) this helps application of angular force
  • c)the rotational effect is caused by the couple formed
  • d)the force formed by one finger overcomes friction and the other finger the force for the operation
Q.25
Two solid spheres each of mass M and radius R/2 are attached to weightless rod of length 2R, the moment of inertia about the axis passing through the centre of one of the sphere and perpendicular to the length of the rod be [ raj PMT 1996]
ch-6_que_no-143_img_no1.png
  • a)(21MR2) / 5
  • b)(2MR2) / 5
  • c)(5MR2) / 2
  • d)(5MR2) / 21
Q.26
Two masses M and m are attached to a vertical axis by weightless threads of combined length l.They are set in rotational motion in a horizontal plane about this axis with constant angular velocity ω. If the tension in the threads are same during motion, the distance of M from the axis is [ MPPMT 1995]
  • a) Ml/ (M + m)
  • b) ml / (M + m)
  • c) (M + m)l / M
  • d) (M + m)l / m
Q.27
Two rings of the same radius and mass are placed such that their centres are at a common point and their planes are perpendicular to each other. The moment of inertia of the system about an axis passing through the centre and perpendicular to the plane of one of the ring is ( mass of ring=m, radius of ring=r) [ MPPMT 1994]
  • a)½ mr2
  • b) mr2
  • c)(3/2) mr2
  • d)2mr2
Q.28
A disc of radius 33cm is hanged by a point at circumference by horizontal nail. Period of oscillation is 1.42 seconds, value of g by this experiment will be [ Raj. PMT 1997]
  • a) 9.25 m/s2
  • b) 9.68 m/s2
  • c)9.86 m/s2
  • d)100 m/s2
Q.29
A smooth wire is bent into a vertical circle of radius a. A bead P can slide smoothly on the wire. The circle is rotated about diameter AB as axis with speed ω as shown in figure . the bead P is at rest with respect to the circular ring in the position shown. Then ω2 is equal to
ch-6_que_no-147_img_no1.png
  • a)2g/a
  • b)2g/(a√3)
  • c)g√3 /a
  • d)2a/ (g√3)
Q.30
The moment of inertia of rod ( length l, mass m) about an axis perpendicular to the length of the rod and passing through a point equidistant from its mid-point and one end is [ MPPMT 1999]
  • a) ml2 / 12
  • b) 7ml2 / 48
  • c) 13ml2 / 48
  • d) 19ml2 / 48
0 h : 0 m : 1 s