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
The radius of gyration of a circular loop of radius r and mass m rotating about its diameter as axis is
  • A
    R
  • B
    \(\surd \) (2)R
  • C
    R/\(\surd \) (2)
    Correct
  • D
    R/2
2
In an orbital motion, the angular momentum vector is
  • A
    parallel to the linear momentum
  • B
    in the orbital plane
  • C
    perpendicular to the orbital plane
    Correct
  • D
    along the radius vector
3
The moment of inertia of a circular disc of mass M and radius R rotating about an axis passing through its edge and perpendicular to the plane of the disc is
  • A
    \({\rm{M}}{{\rm{R}}^{\rm{2}}}\)
  • B
    \({\rm{M}}{{\rm{R}}^{\rm{2}}}\)/2
  • C
    2 \({\rm{M}}{{\rm{R}}^{\rm{2}}}\)
  • D
    (3/2) \({\rm{M}}{{\rm{R}}^{\rm{2}}}\)
    Correct
4
A constant torque acting on a uniform circular wheel changes its angular momentum from \({{\rm{A}}_0}\) to 4 \({{\rm{A}}_0}\) in 4 seconds. The magnitude of the torque is
  • A
    12 \({{\rm{A}}_0}\)
  • B
    3 \({{\rm{A}}_0}\)/4
    Correct
  • C
    4 \({{\rm{A}}_0}\)
  • D
    \({{\rm{A}}_0}\)
5
The moment of inertia of a circular ring about an axis passing through its centre and normal to its plane is 200 gm \({\rm{c}}{{\rm{m}}^{\rm{2}}}\). Then its moment of inertia about a diameter is
  • A
    200 gm \({\rm{c}}{{\rm{m}}^{\rm{2}}}\)
  • B
    400 gm \({\rm{c}}{{\rm{m}}^{\rm{2}}}\)
  • C
    100 gm \({\rm{c}}{{\rm{m}}^{\rm{2}}}\)
    Correct
  • D
    300 gm \({\rm{c}}{{\rm{m}}^{\rm{2}}}\)
6
A dancer on ice spins faster when she folds her hands. This is due to
  • A
    increase in energy and decrease in angular momentum
  • B
    constant angular momentum and increase in kinetic energy
    Correct
  • C
    increase in energy and increase in angular momentum
  • D
    decrease in friction at the skates
7
A uniform rod of mass 2 kg is 1 meter long. Its radius of gyration about an axis through its one end and perpendicular to its length in SI units is
  • A
    1/\(\surd \) (3)
    Correct
  • B
    1/ 2\(\surd \) (3)
  • C
    2 /\(\surd \) (3)
  • D
    2/3
8
Two discs of the same mass and same thickness t are made from two different materials of densities \({{\rm{d}}_{\rm{1}}}\)and \({{\rm{d}}_{\rm{2}}}\)respectively. The ratio of the moments of inertia of the two about an axis passing through the centre and perpendicular to the plane of lamina is
  • A
    \({{\rm{d}}_{\rm{2}}}\) : \({{\rm{d}}_{\rm{1}}}\)
    Correct
  • B
    1: \({{\rm{d}}_{\rm{1}}}\) \({{\rm{d}}_{\rm{2}}}\)
  • C
    \({{\rm{d}}_{\rm{1}}}\) : \({{\rm{d}}_{\rm{2}}}\)
  • D
    \({{\rm{d}}_{\rm{1}}}\) / \({{\rm{d}}_{\rm{2}}}\): 1
9
Four spheres each of mass M and radius R are placed with their centers on the four corners of a square of side 'b'. The moment of inertia of the system about any side of the square is
  • A
    8/5 \({\rm{M}}{{\rm{R}}^{\rm{2}}}\) + \({\rm{M}}{{\rm{b}}^{\rm{2}}}\)
  • B
    8/5 \({\rm{M}}{{\rm{R}}^{\rm{2}}}\) + 2 \({\rm{M}}{{\rm{b}}^{\rm{2}}}\)
    Correct
  • C
    8/5 \({\rm{M}}{{\rm{R}}^{\rm{2}}}\) + 4 \({\rm{M}}{{\rm{b}}^{\rm{2}}}\)
  • D
    4/3 \({\rm{M}}{{\rm{R}}^{\rm{2}}}\)+ 2 \({\rm{M}}{{\rm{b}}^{\rm{2}}}\)
10
When a mass is rotating in a plane about a fixed point, its angular momentum is directed along
  • A
    the radius
  • B
    A line at an angle of 45o to the plane of rotation
  • C
    The tangent to the orbit
  • D
    the axis of rotation
    Correct
11
A mass is revolving in a circle, which is in the plane of paper. The direction of angular acceleration if any, is
  • A
    upward from the plane of paper
  • B
    towards the radius
  • C
    At right angles to the plane of paper
    Correct
  • D
    Tangential
12
Which of the following has the largest moment of inertia?
  • A
    Bar magnet about any axis passing through its centre of mass
  • B
    Ring about an axis perpendicular to its plane
    Correct
  • C
    Solid sphere about any axis passing through its centre of mass
  • D
    Disc about an axis perpendicular to its plane
13
A spherical solid ball of 1 kg. mass and radius 3 cm is rotating about an axis passing through its centre with an angular velocity of 50 radians/s. The kinetic energy of rotation is
  • A
    45000 J
  • B
    920 J
  • C
    (9/20)J
    Correct
  • D
    910 J
14
With reference to the figure below which shows a particle moving along a straight line , y axis represents the position and x axis represents time, if \({{\rm{x}}_{\rm{2}}}\) = 280m, The instantaneous velocity at \({{\rm{x}}_{\rm{2}}}\) in m/s is
Question 14 figure 1
  • A
    138
  • B
    130
  • C
    145
  • D
    127.0
    Correct
15
If a gymnast sitting on a rotating stool with his arms outstretched, suddenly lowers his hands
  • A
    the angular velocity decreases
  • B
    his moment of inertia decreases
    Correct
  • C
    the angular momentum increases
  • D
    the angular velocity stays constant