1. | \(0.75\) m | 2. | \(2.25\) m |
3. | \(1.25\) m | 4. | \(1.875\) m |
Let and be moments of inertia of a body about two axes, A and B, respectively. The axis A passes through the centre of mass of the body, but B does not. Which of the following is correct?
1. <
2. If <, the axes are parallel.
3. If the axes are parallel, <
4. If the axes are not parallel,
Three-point masses each of mass \(m,\) are placed at the vertices of an equilateral triangle of side \(a.\) The moment of inertia of the system through a mass \(m\) at \(O\) and lying in the plane of \(COD\) and perpendicular to \(OA\) is:
1. | \(2ma^2\) | 2. | \({2 \over 3}ma^2\) |
3. | \({5 \over 4}ma^2\) | 4. | \({7 \over 4}ma^2\) |
Two discs are rotating about their axes, normal to the discs and passing through the centres of the discs. Disc D has a 2 kg mass, 0.2 m radius, and an initial angular velocity of 50 rad s. Disc D has 4 kg mass, 0.1 m radius, and initial angular velocity of 200 rad s. The two discs are brought in contact face to face, with their axes of rotation coincident. The final angular velocity (in rad.s) of the system will be:
1. 60
2. 100
3. 120
4. 40
1. \(I_2=I_3>I_1\)
2. \(I_1>I_2>I_3\)
3. \(I_2=I_3<I_1\)
4. \(I_1<I_2<I_3\)
Three identical spherical shells, each of mass m and radius r, are placed as shown in the figure. Consider an axis XX’, which is touching two shells and passes through the diameter of the third shell. The moment of inertia of the system consisting of these three spherical shells about the XX' axis is:
1.mr2
2. 3mr2
3. mr2
4. 4mr2
When a mass is rotating in a plane about a fixed point, its angular momentum is directed along:
1. | a line perpendicular to the plane of rotation |
2. | the line making an angle of \(45^\circ\) to the plane of rotation |
3. | the radius |
4. | the tangent to the orbit |
A circular platform is mounted on a frictionless vertical axle. Its radius is R = 2m and its moment of inertia about the axle is 200 kg m2. Initially, it is at rest. A 50 kg man stands on the edge of the platform and begins to walk along the edge at a speed of 1 m s–1 relative to the ground. The time taken by the man to complete one revolution is:
1.
2.
3.
4.
1. | \(9.9\) m | 2. | \(10.1\) m |
3. | \(10\) m | 4. | \(20\) m |
1. \(\dfrac{\rho L^3}{8\pi^2}\)
2. \(\dfrac{\rho L^3}{16\pi^2}\)
3. \(\dfrac{5\rho L^3}{16\pi^2}\)
4. \(\dfrac{3\rho L^3}{8\pi^2}\)