Contents

**NEET Physics Chapter Wise Mock Test – System of Particle and Rigid Body**

**Question 1:
**In the HCI molecule, the separation between the nuclei of the two atoms is about 1.27Å (1 Å = 10

^{-10}m). Given that, chlorine atom is about 35.5 times as massive as a hydrogen atom and all the mass of the atom is concentrated in its nucleus. The approximate location of centre of mass w.r.t. H atom is

(a) 1 Å

(b) 1.24 Å

(c) 10-10 Å

(d) 10-5 Å

**Question 2:
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**Question 3:
**Two spherical bodies of mass M and 5 M and radii R and 2 R respectively are released in free space with initial separation between their centre equal to 12 R If they attract each other due to gravitational force only, then the distance covered by the smaller body just before collision is

(a) 1.5 R

(b) 2.5 R

(c) 4.5 R

(d) 7.5 R

**Question 4:
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**Question 5:
**If linear density of a rod of length 3m varies as λ= 2 + x, then the position of the centre of gravity of the rod is

(a) 7/3 m

(b) 12/7 m

(c) 10/7 m

(d) 9/7 m

**Question 6:
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**Question 7:
**A particle of mass 2 kg moving with a velocity 5i m/s collides head on with another particle of mass 3kg moving with a velocity -2i m/s. After the collision, the first particle has speed of 1.6i m/s in negative x-direction. Then, velocity of second particle after collision is

(a) 0 m/s

(b) 2.4 i m/s

(c) 5i m/s

(d) 10i m/s

**Question 8:
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**Question 9:
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**Question 10:
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**Question 11:
**The instantaneous angular position of a point on a rotating wheel is given by the equation θ(t) = 2 t

^{3}-6t

^{2}. The torque on the wheel becomes zero at

(a) t= 0.5 s

(b) t = 0.25 s

(c) t = 2 s

(d) t= 1s

**Question 12:
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**Question 13:
**The moment of inertia of a uniform circular disc of radius R and mass M about an axis passing from the edge of the disc and normal to the disc is

(a) 1/2 MR

^{2}

(b) MR

^{2}

(c ) 7/2 MR

^{2}

(d) 3/2 MR

^{2}

**Question 14:
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**Question 15:
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**Question 16:
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**Question 17:
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**Question 18:
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**Question 19:
**Velocity of centre of mass of two particles is v and the sum of the masses of two particles is m. Which of the following statement is correct?

(a) Kinetic energy willl be equal to 1/2mv

^{2}

(b) Kinetic energy will always be less than 1/2mv

^{2}

(c) Kinetic energy will be greater than or equal to 1/2mv

^{2}

(d) Kinetic energy will always be greater than 1/2mv

^{2}

**Question 20:
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**Question 21:
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**Question 22:
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**Direction (Q. NOS. 23-26):** In each of the following questions a statement of Assertion is given followed by a corresponding statement of Reason just below it. Of the statement mark the correct answer as

(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion

(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion

(c) If Assertion is true but Reason is false

(d) If both Assertion and Reason are false

**Question 23:
Assertion (A): **The centre of mass of a system of n-particles is the weighed average of the position vector of the n-particles making up the system.

**The position of the centre of mass of the system is independent of a coordination system.**

Reason (R):

Reason (R):

**Question 24:
Assertion (A): **The total kinetic energy of a rolling solid sphere is the sum of translational and rotational kinetic energies.

**For all solid bodies total kinetic energy is always twice translational kinetic energy.**

Reason (R):

Reason (R):

**Question 25:
Assertion (A): **There are very small sporadic changes in the speed of rotation of the earth.

**Shifting of large air masses in the earth’s atmosphere produce a change in the moment of inertia of the earth causing its speed of rotation to change.**

Reason (R):

Reason (R):

**Question 26:
Assertion (A): **The centre of mass of an electron and proton, when released moves faster towards proton.

**Proton moves faster than electron.**

Reason (R):

Reason (R):

**Question 27:
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**Question 28:
**A small object of uniform density rolls up a curved surface with an initial velocity v. It reaches upto a

maximum height of 3v

^{2}/4g with respect to the initial position. The object is

(a) ring

(b) solid sphere

(c) hollow sphere

(d) disc

**Question 29:
**Moment of inertia of circular loop of radius ft about the axis of rotation parallel to horizontal diameter at a distance R/2 from it is

(a) MR

^{2}

(b) 1/2 MR

^{2}

(c) 2 MR

^{2}

(d) 3/4MR

^{2}

**Question 30:
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**Question 31:
**The moment of inertia of a circular loop of radius R, at a distance of R/2 around a rotating axis parallel to horizontal diameter of loop is

(a) MR

^{2}

(b)1/2 MR

^{2}

(c) 2 MR

^{2}

(d) 3/4 MR

^{2}

**Question 32:
**The radius of gyration of a body about an axis at a distance 6 cm from its centre of mass is 10 cm. Then, its radius of gyration about a parallel axis through its centre of mass will be

(a) 800 cm

(b) 8 cm

(c) 0.8 cm

(d) 80 cm

**Question 33:
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**Question 34:
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**Question 35:
**From a circular disc of radius R and mass 9M, a small disc of radius R/3 is removed from the disc, the moment of inertia of the remaining disc about an axis perpendicular to the plane of the disc and passing through O is

**(a) 4MR2**

(b) 40/9 MR2

(c) 10 MR2

(d) 37/9 MR2

### Answers:

### Hints And Solutions: