System Of Particles And Rotational Motion CBSE Questions & Answers

System Of Particles And Rotational Motion

This is Physics Class 11 System of Particles and Rotational Motion CBSE Questions & Answers. There are 15 questions in this test with each question having around four answer choices.

Questions & Answers

1
Torque \(\tau \) is defined in terms of position vector \(r\) and the force acting F as
  • A
    \(\tau = r \times F\)
    Correct
  • B
    \(\tau = F \times r\)
  • C
    \(\tau = r.r \times F\)
  • D
    \(\tau = r \times F.r\)
2
The angular momentum l of the particle having a position vector \(r\) and linear momentum \(p\), with respect to the origin O is defined to be
  • A
    \(l = r \times r \times p\)
  • B
    \(l = r \times p\)
    Correct
  • C
    \(l = r \times p.\omega \)
  • D
    \(l = r \times p \times r\)
3
Torque \(\tau \) and angular momentum \(l\) are related by
  • A
    \(\tau = 2{{dl} \over {dt}}\)
  • B
    \(\tau = {{dl} \over {dt}}\)
    Correct
  • C
    \(\tau = {{{d^2}l} \over {d{t^2}}}\)
  • D
    \(\tau = {{{d^3}l} \over {d{t^3}}}\)
4
A rigid body is in mechanical equilibrium if
  • A
    \(\mathop \sum \nolimits^ {F_i} = 0and\mathop \sum \nolimits^ {\tau _i} = 0\)
    Correct
  • B
    \(\mathop \sum \nolimits^ {F_i} \ne 0and\mathop \sum \nolimits^ {\tau _i} \ne 0\)
  • C
    \(\mathop \sum \nolimits^ {F_i} \ne 0and\mathop \sum \nolimits^ {\tau _i} = 0\)
  • D
    \(\mathop \sum \nolimits^ {F_i} = 0and\mathop \sum \nolimits^ {\tau _i} \ne 0\)
5
Centre of gravity can be defined
  • A
    as the center of mass
  • B
    as that point where the total gravitational torque on the body is greater than zero
  • C
    as that point where the total gravitational force on the body is zero
  • D
    as that point where the total gravitational torque on the body is zero
    Correct
6
Analogue of mass in rotational motion is
  • A
    rotary mass
  • B
    angular acceleration
  • C
    moment of inertia
    Correct
  • D
    torque
7
The radius of gyration of a body about an axis may be defined as the
  • A
    distance from the center of gravity to the center of mass
  • B
    distance from the axis of a mass point whose mass is equal to the mass of the whole body and whose moment of inertia is equal to the moment of inertia of the body about the axis
    Correct
  • C
    distance from the center of mass to the axis of rotation
  • D
    distance from the center of gravity to the axis of rotation
8
the moment of inertia of a planar body (lamina) about an axis perpendicular to its plane is.
  • A
    equal to the sum of its moments of inertia about two perpendicular axes concurrent with perpendicular axis and lying in the plane of the body
    Correct
  • B
    equal to the its moments of inertia about an axis perpendicular to the axis of rotation axis and lying in the plane of the body
  • C
    equal to the average of its moments of inertia about three perpendicular axes concurrent with perpendicular axis and lying in the plane of the body
  • D
    equal to the difference of its moments of inertia about two perpendicular axes concurrent with perpendicular axis and lying in the plane of the body
9
The moment of inertia of a body about any axis is
  • A
    equal to the sum of the moment of inertia of the body about a parallel axis passing through its centre of mass and the product of its mass and the square of the distance between the two parallel axes.
    Correct
  • B
    equal to the sum of the moment of inertia of the body about any axis passing through its centre of mass and the product of its mass and the square of the distance between the two parallel axes.
  • C
    equal to the difference of the moment of inertia of the body about a parallel axis passing through its centre of mass and the product of its mass and the square of the distance between the two parallel axes.
  • D
    equal to the average of the moments of inertia of the body about a parallel axis passing through its centre of mass and the product of its mass and the square of the distance between the two parallel axes.
10
The angular acceleration of a rigid body \({\bf{\alpha }}\) rotating about a fixed axis is given by (I is the moment of inertia and \({\bf{\tau }}\) is the torque)
  • A
    \({\rm{I}}\alpha \) = \({\bf{\tau }}\)
    Correct
  • B
    \({\rm{I}}\alpha \) = \(\tau /{\rm{3}}\)
  • C
    \({\rm{I}}\alpha \) = \({\rm{2}}\tau \)
  • D
    \({\rm{I}}\alpha \) = \(\tau /{\rm{2}}\)
11
For rolling motion without slipping the kinetic energy of the body is
  • A
    equal to the sum of kinetic energies of translation and rotation
    Correct
  • B
    equal to the difference of kinetic energies of translation and rotation
  • C
    equal to the kinetic energy of translation
  • D
    equal to the kinetic energy of rotation
12
A solid sphere of mass M and radius R spins about an axis passing through its centre making 600 rpm. Its kinetic energy of rotation is
  • A
    \({\rm{8}}0{\rm{ }}{\pi ^{\rm{2}}}{\rm{M}}{{\rm{R}}^{\rm{2}}}\)
    Correct
  • B
    \({\rm{2}}/{\rm{5 }}\pi {\rm{ }}{{\rm{M}}^{\rm{2}}}{{\rm{R}}^{\rm{2}}}\)
  • C
    \({\rm{8}}0{\rm{ }}\pi {\rm{ MR}}\)
  • D
    \({\rm{2}}/{\rm{5 }}{\pi ^{\rm{2}}}{\rm{MR}}\)
13
A child swinging on a swing in a sitting position stands up. Then, the time period of the swing will
  • A
    Increase if the child is tall and decrease if the child is short.
  • B
    Remains the same
  • C
    Decrease
    Correct
  • D
    Increase
14
Angular momentum is
  • A
    None of these
  • B
    A polar vector
  • C
    A scalar
  • D
    An axial vector
    Correct
15
Angular momentum of a body is defined as the product of
  • A
    Mass and angular velocity
  • B
    Centripetal force and radius
  • C
    Moment of inertia and angular velocity
    Correct
  • D
    Linear velocity and angular velocity