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Question (1)

QN0035283

If the resultant of all external forces is zero, then velocity of centre of mass will be

(A)
zero
(B)
constan
(C)
either (a) or (b
(D)
neither (a) nor (b)

Correct Answer: C

Explanation:

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Question (2)

QN0035284

Four particles A, B, C and D with masses , and are at the corners of a square. They have accelerations of equal magnitude with directions as shown. The acceleration of the centre of mass of the particles is:

(A)
(B)
(C)
Zero
(D)

Correct Answer: A

Explanation:

Acceleration of centre of mass is given by

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Question (3)

QN0035285

There are some passengers inșide a stationary railway compartment. The centre of mass of the compartment itself (without the passengers) is , while the centre of mass of the 'compartment plus passengers' system is . If the passengers move about inside the compartment then

(A)
both and will move with respect to the ground
(B)
neither nor will be stationary with respect to the ground
(C)
will move but will be stationary with respect to the ground
(D)
will move but will be stationary with respect to the ground

Correct Answer: C

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Question (4)

QN0035286

A body of mass while falling vertically downwards under gravity breaks into two parts; a body B of mass and a body of mass . The centre of mass of bodies and taken together shifts compared to that of body

(A)
does not shift
(B)
depends on height of breaking
(C)
towards body B
(D)
towards body

Correct Answer: A

Explanation:

Does not shift as no external force acts. The centre of mass of the system continues its original path. It is only the internal forces which comes into play while breaking

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Question (5)

QN0035287

Two particles of mass and attract each other with a force inversely proportional to the square of the distance between them. If the particles are initially held at rest and then released, the centre of mass will

(A)
move towards
(B)
move towards
(C)
remains at rest
(D)
None of these

Correct Answer: C

Explanation:

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Question (6)

QN0035288

A shell following a parabolic path explodes somewhere in its flight. The centre of mass of fragments will continue to move in

(A)
vertical direction
(B)
any direction
(C)
horizontal direction
(D)
same parabolic path

Correct Answer: D

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Question (7)

QN0035289

A man stands at one end of a boat which is stationary in water. Neglect water resistance. The man now moves to the other end of the boat and again becomes stationary. The centre of mass of the 'man plus boat' system will remain stationary with respect to water

(A)
in all cases
(B)
only when the man is stationary initially and finally
(C)
only if the man moves without acceleration on the boat
(D)
only if the man and the boat have equal masses

Correct Answer: A

Explanation:

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Question (8)

QN0035290

Two bodies of masses and are moving with velocities and respectively along same direction. Then the velocity of their centre of mass will be

(A)
(B)
(C)
(D)

Correct Answer: B

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Question (9)

QN0035291

Two objects and initially at rest move towards each other under mutual force of attraction. At the instant when the velocity of is and that of is , the velocity of centre of mass of the system is

(A)
(B)
(C)
(D)
zero

Correct Answer: D

Explanation:

Centre of mass is at rest

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Question (10)

QN0035292

In rotatory motion, linear velocities of all the particles of the body are

(A)
same
(B)
different
(C)
zero
(D)
cannot say

Correct Answer: B

Explanation:

linear velocities (v) for particles at different distances (r) from the axis of rotation are different.

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Question (1)

If the resultant of all external forces is zero, then velocity of centre of mass will be

Explanation:

Link:

Question (2)

Four particles A, B, C and D with masses , and are at the corners of a square. They have accelerations of equal magnitude with directions as shown. The acceleration of the centre of mass of the particles is:

Explanation:

Link:

Question (3)

There are some passengers inșide a stationary railway compartment. The centre of mass of the compartment itself (without the passengers) is , while the centre of mass of the 'compartment plus passengers' system is . If the passengers move about inside the compartment then

Explanation:

Link:

Question (4)

A body of mass while falling vertically downwards under gravity breaks into two parts; a body B of mass and a body of mass . The centre of mass of bodies and taken together shifts compared to that of body

Explanation:

Link:

Question (5)

Two particles of mass and attract each other with a force inversely proportional to the square of the distance between them. If the particles are initially held at rest and then released, the centre of mass will

Explanation:

Link:

Question (6)

A shell following a parabolic path explodes somewhere in its flight. The centre of mass of fragments will continue to move in

Explanation:

Link:

Question (7)

A man stands at one end of a boat which is stationary in water. Neglect water resistance. The man now moves to the other end of the boat and again becomes stationary. The centre of mass of the 'man plus boat' system will remain stationary with respect to water

Explanation:

Link:

Question (8)

Two bodies of masses and are moving with velocities and respectively along same direction. Then the velocity of their centre of mass will be

Explanation:

Link:

Question (9)

Two objects and initially at rest move towards each other under mutual force of attraction. At the instant when the velocity of is and that of is , the velocity of centre of mass of the system is

Explanation:

Link:

Question (10)

In rotatory motion, linear velocities of all the particles of the body are

Explanation:

Link:

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