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CBSE

Subject

Physics

NEET Physics : System of Particles and Rotational Motion

Multiple Choice Questions

51.

A force of $- F \hat{k}$ acts on O, the origin of the coordinate systems. The torque about the point (1, -1 ) is

$F (\hat{i} - \hat{j})$
$- F (\hat{i} + \hat{j})$
$F (\hat{i} + \hat{j})$
$- F (\hat{i} - \hat{j})$

52.

The radius of gyration of a body about an axis at a distance 6 cm from its centre of mass is 10 cm. Then, its radius of gyration about a parallel axis through its centre of mass will be

80 cm
8 cm
0.8 cm
80 m

53.

The equation of stationary wave along a stretched string is given by $y = 5 \sin \frac{πx}{3} \cos 40 πt$ where, x and y are in cm and t in second. The separation between two adjacent nodes is :

1.5 cm
3 cm
6 cm
4 cm

54.

If the angle between the vectors $\vec{A} and \vec{B} is θ$ , the value of the product $(\vec{B} \times \vec{A}) . \vec{A}$ is equal to

${BA}^{2} cosθ$
BA² sinθ
BA² sinθ cosθ
zero

55.

The angular momentum of a rotating body changes from A_o to 4A_o in 4 minutes. The torque acting on the body is:

3/4 A_o
4A_o
3A_o
3/2A_o

56.

The moment of inertia of a uniform circular disc of radius R and mass M about an axis passing from the edge of the disc and normal to the disc is

$\frac{1}{2} {MR}^{2}$
MR²
$\frac{7}{2} {MR}^{2}$
$\frac{3}{2} {MR}^{2}$

57.

Point masses 1, 2, 3 and 4 kg are lying at the points (0, 0, 0), (2, 0, 0), (0, 3, 0) and (- 2, -2, 0) respectively. The moment-of inertia of this system about X-axis will be

43 kg-m²
34 kg-m²
27 kg-m²
72 kg-m²

58.

The moment of inertia of a uniform circular disc of radius R and mass M about an axis passing from the edge of the disc and normal to the disc is

MR²
$\frac{1}{2} {MR}^{2}$
$\frac{3}{2} {MR}^{2}$
$\frac{7}{2} {MR}^{2}$

59.

If a spherical ball rolls on a table without slipping the friction of its total energy associated with rotational energy is :

60.

The speed of earth's rotation about its axis is o. Its speed is increased to x times to make the effective acceleration due to gravity equal to zero at the equator. Then x is

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