Q.1.
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]
-
50%
a) 4500J
-
25%
b) 90J
-
0%
c) 9×10-3 J
-
25%
d) (9/20) J
Q.2.
The quantity which remains constant in conservative field if [ Raj.PET 1996]
-
0%
a)Potential energy
-
20%
b) Kinetic energy
-
60%
c)Angular momentum
-
20%
d)Linear momentum
Q.3.
A body is moving with a constant velocity, then which of the following statement is correct :
-
20%
a) the body necessarily a constant angular momentum
-
0%
b) the body has necessarily a constant moment of inertia
-
20%
c)the body has necessarily a constant angular speed and moment of inertia
-
60%
d)the angular speed and moment of inertia may vary but their product is constant
Q.4.
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]
-
25%
a) 3.2 m/s
-
75%
b) 5.4 m/s
-
0%
c) 7.6 m/s
-
0%
d) 9.2 m/s
Explanation
Q.5.
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
-
25%
a) (g/L)
-
25%
b) 2(g/L)
-
0%
c) (2/3)(g/L)
-
50%
d) (3/2)(g/L)
Q.6.
Angular momentum of the body is conserved [ MPPET 1995]
-
0%
a) Always
-
0%
b) never
-
0%
c) in presence of external torque
-
100%
d) in absence of external torque
Q.7.
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]
-
25%
a) d1 > d2
-
50%
b) R1 > R2
-
0%
c)d1> d2 and R1 > R2
-
25%
d)d1 < d2 and R1 < R2
Q.8.
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]
-
75%
a)6I /5
-
25%
b)3I/4
-
0%
c)3I/2
-
0%
d)5I/4
Q.9.
The rotational and translation kinetic energy of rolling body are same, the body is [ RajPET 1996]
-
0%
a) Disc
-
50%
b) Sphere
-
0%
c) Cylinder
-
50%
d) Ring
Q.10.
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]
-
50%
a)1.0 ms2
-
25%
b) 0.5 ms2
-
25%
c)1.5 ms2
-
0%
d)2.0 ms2
Q.11.
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]
-
25%
a)
-
50%
b)
-
0%
c)
-
25%
d)
Q.12.
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
-
50%
a)
-
0%
b)
-
50%
c)
-
0%
d)
Explanation
Q.13.
Before jumping in water from above a swimmer bends his body to [ MPPMT 1994]
-
0%
a) increase moment of inertia
-
50%
b) decrease moment of inertia
-
25%
c) decrease the angular momentum
-
25%
d) reduce the angular velocity
Q.14.
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
-
0%
a)zero
-
75%
b) 30 units
-
25%
c)75 units
-
0%
d)40√2 units
Explanation
Q.15.
A tap can be operated easily using two fingers because : [ UGET 1995]
-
25%
a) the force available for the operation will be more
-
0%
b) this helps application of angular force
-
50%
c)the rotational effect is caused by the couple formed
-
25%
d)the force formed by one finger overcomes friction and the other finger the force for the operation
Q.16.
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]
-
75%
a)(21MR2) / 5
-
25%
b)(2MR2) / 5
-
0%
c)(5MR2) / 2
-
0%
d)(5MR2) / 21
Q.17.
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]
-
50%
a) Ml/ (M + m)
-
50%
b) ml / (M + m)
-
0%
c) (M + m)l / M
-
0%
d) (M + m)l / m
Explanation
Q.18.
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]
-
25%
a)½ mr2
-
0%
b) mr2
-
75%
c)(3/2) mr2
-
0%
d)2mr2
Explanation
Q.19.
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]
-
0%
a) 9.25 m/s2
-
50%
b) 9.68 m/s2
-
50%
c)9.86 m/s2
-
0%
d)100 m/s2
Explanation
Q.20.
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
-
25%
a)2g/a
-
75%
b)2g/(a√3)
-
0%
c)g√3 /a
-
0%
d)2a/ (g√3)
Explanation
Q.21.
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]
-
25%
a) ml2 / 12
-
25%
b) 7ml2 / 48
-
25%
c) 13ml2 / 48
-
25%
d) 19ml2 / 48
Q.22.
railway tracks are banked on curves so that
-
0%
a)no frictional force may be produced between the track and wheels
-
25%
b) the train may not fall down inward
-
75%
c)necessary centripetal force may be obtained from the horizontal component of normal reaction due to the track
-
0%
d)none of the above
Q.23.
A motor cyclist rides on cylindrical wall of velodrome ( hollow metal cylinder kept with the axis vertical) of radius r rotating about its axis at the rate f rev/sec. the least coefficient of friction necessary so that he does not step down is
-
25%
a) g / (4π2f2r)
-
25%
b) (4π2f2r) / r
-
50%
c)(4π2f2) / gr
-
0%
d)gr/(4π2r2)
Explanation
Q.24.
If a particle of mass 'm' is moving in a horizontal circle of radius 'r' with a centripetal force ( -1/r2) the total energy is [ JIPMER 1998]
-
100%
a)-1/2r
-
0%
b) -1/r
-
0%
c)-2/r
-
0%
d)-4/r
Q.25.
A particle of mass m is executing uniform circular motion on a path of radius r. If p is the magnitude of its linear momentum, the radial force acting on the particle is : [ MPPMT 1994]
-
0%
a) pmr
-
0%
b) rm/p
-
25%
c) mp2 /r
-
75%
d) p2 / rm
Q.26.
A body of mass m hangs at one end of string of length l, the other end of which is fixed. It is given a horizontal velocity so that the string would just become slack, when it makes an angle of 60° with the upward drawn vertical. The tension in the string at this position is [ ISM Dhanbad 1994]
-
75%
a) 4.5 mg
-
0%
b) mg
-
25%
c)3m
-
0%
d)√3 mg
Explanation
Q.27.
A particle of mass m is moving in a circular path of constant radius r such that its centripetal acceleration a is varying with time t, a=k2rt2 where k is a constant. The power delivered to the particle by the forces acting on it is [ IIT 1994]
-
0%
a) 2πmk2r2t
-
50%
b) mk2r2t
-
0%
c)(mk4r2t5) / 3
-
50%
d)zero
Q.28.
The tension in the string revolving in a vertical circle with a mass m at the end which is .. [ EAMCET 1995]
-
25%
a) mv2 / r
-
0%
b) (mv2 / r) - mg
-
75%
c)(mv2 / r) + mg
-
0%
d)mg
Q.29.
A pendulum is suspended from the ceiling of a car rotating in ac circular path with an acceleration of 0.49m/sThe angle which the string makes with the vertical is
-
25%
a) tan-1 ( 1/√3)
-
0%
b) tan-1√3
-
75%
c) tan-1 0.05
-
0%
d) tan-1 0.005
Explanation
Q.30.
The string of pendulum of length l is displaced through 90° from the vertical and released. then the minimum strength of the string in order to withstand the tension, as the pendulum passes through the mean position is [ MP 1986]
-
0%
a)mg
-
75%
b) 3mg
-
0%
c)5mg
-
25%
d)6mg
Explanation
