A small mass attached to a string rotates on a frictionless table top as shown. If the tension on the string is increased by pulling the string causing the radius of the circular motion to decrease by a factor of 2, the kinetic energy of the mass will

                              

1. Increase by a factor of 4                                       

2. Decrease by a factor of 2

3. Remain constant                                                   

4. Increase by a factor of 2 

Three-point masses 'm' each, are placed at the vertices of an equilateral triangle of side a. Moment of inertia of the system about axis COD is-

1. $2m{a}^2$

2. $\frac{2}{3}m{a}^2$

3. $\frac{5}{4}m{a}^2$

4. $\frac{7}{4}m{a}^2$

A particle is moving in a circular orbit with constant speed. Select wrong alternate

1. Its linear momentum is conserved

2. Its angular momentum is conserved

3. It is moving with variable velocity

4. It is moving with variable acceleration

One solid sphere A and another hollow sphere B are of same mass and same outer radii. Their moment of inertia about their diameters are respectively I_A and I_B such that

1. ${\mathrm{I}}_{\mathrm{A}}={\mathrm{I}}_{\mathrm{B}}$

2. ${\mathrm{I}}_{\mathrm{A}}>{\mathrm{I}}_{\mathrm{B}}$

3. ${\mathrm{I}}_{\mathrm{A}}<{\mathrm{I}}_{\mathrm{B}}$

4. $\frac{{\mathrm{I}}_{\mathrm{A}}}{{\mathrm{I}}_{\mathrm{B}}}=\frac{d_A}{d_B}$

A particle of mass 1 kg is kept at (1m, 1m, 1m). The moment of inertia of this particle about z-axis would be

1.  $1 \mathrm{kg}-{\mathrm{m}}^2$

2.  $2 \mathrm{kg}-{\mathrm{m}}^2$

3.  $3 \mathrm{kg}-{\mathrm{m}}^2$

4.  None of these

A horizontal platform is rotating with uniform angular velocity around the vertical axis passing through its centre. At some instant of time a viscous fluid of mass 'm' is dropped at the centre and is allowed to spread out and finally fall. The angular velocity during this period

1. Decreases continuously

2. Decreases initially and increases again

3. Remains unaltered

4. Increases continuously

For L = 3.0 m, the total torque about pivot A provided by the forces as shown in the figure is:

For the same total mass, which of the following will have the largest moment of inertia about an axis passing through the centre of gravity and perpendicular to the plane of the body?

1. A disc of radius a

2. a ring of radius a

3. a square lamina of side 2 a

4. four rods forming square of side 2 a.

The radius of gyration of a uniform rod of length L about an axis passing through its centre of mass is

1. $\frac{L}{2\sqrt{3}}$

2. $\frac{L^2}{12}$

3. $\frac{L}{\sqrt{3}}$

4. $\frac{L}{\sqrt{2}}$