The direction of the angular velocity vector is along

• the tangent to the circular path

• the inward radius

• the outward radius

• the axis of rotation

A man of mass 60 kg records his wt on a weighing machine placed inside a lift. The ratio of wts. of  man recorded when lift is ascending up with a uniform speed of 2 m/s to when it is descending down with a uniform speed of 4 m/s will be

• 0.5

• 1

• 2

• none of these

103.

The moment of inertia of a rod about an axis through its centre and perpendicular to it is $\frac{1}{12}$ ML² ( where M is the mass and L, the length of the rod). The rod is bent in the middle so that the two halves make an angle of 60^°. The moment of inertia of the bent rod about the same axis would be

• $\frac{1}{48}$ ML²

• $\frac{1}{12}$ML²

• $\frac{1}{24}$ ML²

• $\frac{{\mathrm{ML}}^2}{8\sqrt{3}}$

Assertion:  A judo fighter in order to throw his opponent on to the mat tries to initially bend his opponent and then rotate him around his hip. 

Reason: As the mass of the opponent is brought closer to the fighter's hip, the force required to throw the opponent is reduced.

• If both assertion and reason are true and reason is the correct explanation of the assertion

• If both assertion and reason are true but reason is not the correct explanation of the assertion

• If assertion is true, but reason is false

• Both assertion and reason are false statements

In the figure, the position-time graph of a particle of mass 0.1 kg is shown. The impulse at t = 2 sec is

• 0.2 kg m sec^-1

• - 0.2 kg m sec^-1

• 0.1 kg m sec^-1

• - 0.4 kg m sec^-1

The pressure exerted by an electromagnetic wave of intensity I ( watt/m² ) on a nonreflecting surface is [ c is the velocity of light ]

• Ic

• Ic²

• I/c

• I/c²

A ladder is leaned against a smooth wall and  it is allowed to slip on a frictionless floor. Which figure represents trace of its centre of mass.

Assertion: : For a system of particles under central force field, the total angular momentum is conserved.

Reason:  The torque acting on such a system is zero.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false

In an orbital motion, the angular momentum vector is

• along the radius vector

• parallel to the linear momentum

• in the orbital plane

• perpendicular to the orbital plane

The direction of the angular velocity vector is along

• the tangent to the circular path

• the inward radius

• the outward radius

• the axis of rotation