A man of the mass M stands at one end of a plank of length L which lies at rest on a frictionless surface. The man walks to the other end of the plank. If the mass of the plank is $\frac{\mathrm{M}}{3}$, the distance that the man moves relative to the ground is

1. $\frac{3\mathrm{L}}{4}$

2. $\frac{\mathrm{L}}{4}$

3. $\frac{4\mathrm{L}}{5}$

4. $\frac{\mathrm{L}}{3}$

Ratio of total kinetic energy and rotational kinetic energy in the motion of a disc is

1. 1:1

2. 2:7

3. 1:2

4. 3:1

A cylinder is rolling over a surface. Which points on it move rectilinearly?

1. All points on the curved surface of the cylinder.

2. All points on the flat surfaces of the cylinder.

3. All points on the axis of the cylinder.

4. None of the above

A uniform rod AB of length l and mass m is free to rotate about point A. The rod is released from rest in horizontal position. Given that the moment of inerita of the rod about A is $\frac{{\mathrm{ml}}^2}{3}$ the initial angular acceleration of the rod will be

$1. \frac{2\mathrm{g}}{3\mathrm{l}}$
$2. \mathrm{mg}\frac{\mathrm{l}}{2}$
$3. \frac{3}{2}\mathrm{gl}$
$4. \frac{3\mathrm{g}}{2\mathrm{l}}$

A round disc of the moment of inertia ${\mathrm{l}}_2$ about its axis perpendicular to its plane and passing through its center is placed over another disc of the moment of inertial ${\mathrm{l}}_1$ rotating with an angular velocity $\omega$ about the same axis. The final angular velocity of the combination of discs is

1.  $\frac{{\mathrm{l}}_2\mathrm{\omega }}{{\mathrm{l}}_1 + {\mathrm{l}}_2}$

2.  $\mathrm{\omega }$

3.  $\frac{{\mathrm{l}}_1\mathrm{\omega }}{{\mathrm{l}}_1 + {\mathrm{l}}_2}$

4.  $\frac{\left({\mathrm{l}}_1 + {\mathrm{l}}_2\right)\mathrm{\omega }}{{\mathrm{l}}_1}$

Which of the following will not be affected if the radius of the sphere is increased while keeping mass constant?

A particle of mass 5 g is moving with a uniform speed of $3\sqrt{2}$cm/s in the x-y plane along the line y = $2\sqrt{5}$cm. The magnitude of its angular momentum about the origin in $\mathrm{g}-{\mathrm{cm}}^2/\mathrm{s}$ is

1.  0

2.  30

3.  $30\sqrt{2}$

4.  $30\sqrt{10}$

A mass M is supported by a massless string wound round a uniform cylinder of mass M and radius R. On releasing the mass from rest, it will fall with an acceleration assuming no slipping-

1.  $\frac{\mathrm{g}}{3}$

2.  $\frac{\mathrm{g}}{2}$

3.  $\frac{2\mathrm{g}}{3}$

4.  g

A closed tube partly filled with water lies in a horizontal plane. If the tube is rotated about perpendicular bisector, the moment of inertia of the system

1. increases

2. decreases

3. remains constant

4. depends on sense of rotation

A disc is rotating With an angular speed of m. If a child sits on it, which of the following is conserved? 

1.  kinetic energy 

2.  potential energy 

3.  linear momentum 

4.  angular momentum