The angular momentum of a rotating body changes from Ao to 4Ao in 4 minutes. The torque acting on the body is:
3/4 Ao
4Ao
3Ao
3/2Ao
If a spherical ball rolls on a table without slipping the friction of its total energy associated with rotational energy is :
3/5
2/7
2/5
3/7
The equation of stationary wave along a stretched string is given by 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
If the angle between the vectors , the value of the product is equal to
BA2 sinθ
BA2 sinθ cosθ
zero
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
A force of acts on O, the origin of the coordinate systems. The torque about the point (1, -1 ) is
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
1
8.5
17
34
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
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
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
B.
8 cm
The moment of inertia of a body about any axis is 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.
From the theorem of parallel axis, the moment of inertia I is equal to
where is moment of inertia about the centre of mass and 'a' the distance of axis from the centre.
I = MK2 + M × (6)2
⇒
⇒ (10)2 = K2 + 36
⇒ K2 = 100 - 36
⇒ K2 = 64
⇒ K = 8 cm