### NEET Physics - New - Motion of System of Particles and Rigid Body

#### Question - 1

When a torque acting upon a system is zero. Which of the following will be constant?

• A Force
• B Linear impulse
• C Linear momentum
• D Angular momentum

#### Question - 2

In a spinning top, axis. moves around the vertical through its point of contact with the ground sweeping out a cone. This movement of the axis of the top around the vertical is known as

• A rotation
• B translation
• C precession
• D rolling

#### Question - 3

Two discs of same moment of inertia rotating about their regular axis passing through centre and perpendicular to the plane of disc with angular velocities ${ \omega }_{ 1 }$ and ${ \omega }_{ 2 }$. They are brought into contact face to face coinciding the axis of rotation. The expression for loss of energy during this process is:

• A $\frac { 1 }{ 4 } I{ \left( { \omega }_{ 1 }-{ \omega }_{ 2 } \right) }^{ 2 }$
• B $I{ \left( { \omega }_{ 1 }-{ \omega }_{ 2 } \right) }^{ 2 }$
• C $\frac { 1 }{ 8 } I{ \left( { \omega }_{ 1 }-{ \omega }_{ 2 } \right) }^{ 2 }$
• D $\frac { 1 }{ 2 } I{ \left( { \omega }_{ 1 }+{ \omega }_{ 2 } \right) }^{ 2 }$

#### Question - 4

Two rotating bodies A and B of masses m and 2 m with moments of inertia Iand IB  (IB > IA ) have equal kinetic energy of rotation. If LA and  Lbe their angular momenta respectively, then :

• A LA = LB/2
• B LA = 2LB
• C LB > LA
• D LA > LB

#### Question - 5

A light rod of length I has two masses m1 and  m2 attached to its two ends. The moment of inertia of the system about an axis perpendicular to the rod and passing through the centre of mass is :

• A [m1m2/(m1m2)] $\times$ I2
• B [(m1m2)/m1m2] $\times$ I2
• C (m1 + m2) $\times$ I2
• D $\sqrt{m_1m_2}\times I^2$

#### Question - 6

Point masses m1 and m2 are placed at the opposite ends of a rigid rod of length L, and negligible mass. The rod is to be set rotating about an axis perpendicular to it. The position of point P on this rod through which the axis should pass so that the work required to set the rod rotating with angular velocity $\omega$0 is minimum is given by :

• A x = m2/m1L
• B x = m2L/(m1+m2)
• C x = m1L/(m1+m2)
• D x = m1/m2L

#### Question - 7

Two stones of masses m and 2m are whirled in horizontal circles, the heavier one in a radius r/2 and the lighter one in radius r. The tangential speed of lighter stone is n times that of the value of heavier stone when they experience same centripetal forces. The value of n is :

• A 1
• B 2
• C 3
• D 4

#### Question - 8

A rod PQ of M and length Lis hinged at end P.The rod is held horizontally by a massless string tied to point Q as shown in the figure. When the string is cut, the initial acceleration of the rod is

• A g/L
• B 2g/L
• C 2g/3L
• D 3g/2L

#### Question - 9

The moment ofinertia of a thin uniform rod of mass M and length L about an axis passing through its midpoint and perpendicular to its length is I0, Its moment of inertia about an axis passing through one of its ends and perpendicular to its length is :

• A I0 + (ML2)
• B I0 + (ML2/2)
• C I0 + (ML2/4)
• D I0 + (2ML2)

#### Question - 10

Two bodies of mass 1 kg and 3 kg have position  vectors $\hat{i} + 2\hat{j}+\hat{k}$ and $-3\hat{i} - 2\hat{j}+\hat{k}$ respectively. The centre of mass of this system has a position vector:

• A $-2\hat{i} - \hat{j}+\hat{k}$
• B $2\hat{i} - \hat{j}-2\hat{k}$
• C $-\hat{i} - \hat{j}+\hat{k}$
• D $-2\hat{i}+2\hat{k}$