কেমিক্যাল ইঞ্জিনিয়ারিং

1771. MCQPractice set · Question 31

External impulse zero হলে centre of mass-এর momentum কী?

a.

constant

b.

zero necessarily

c.

infinite

d.

decreases

Correct answer: a

COM momentum total momentum-এর সঙ্গে conserved থাকে।

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1772. MCQPractice set · Question 32

Two-particle system-এর COM velocity কী?

a.

total momentum/total mass

b.

total mass/total momentum

c.

sum of speeds

d.

difference of masses

Correct answer: a

V_COM=P_total/M_total।

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1773. MCQPractice set · Question 33

System-এর total momentum P=0 হলে COM velocity কী?

a.

0

b.

P/M maximum

c.

g

d.

undefined

Correct answer: a

V_COM=P/M=0।

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1774. MCQPractice set · Question 34

Explosion-এর পরে COM-এর motion কীভাবে থাকে, external force না থাকলে?

a.

আগের velocity-তে

b.

সবসময় rest

c.

accelerated

d.

random

Correct answer: a

Internal explosion COM motion বদলায় না।

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1775. MCQPractice set · Question 35

একটি 4 kg object দুই fragment-এ ভাগ হলে total mass কী?

a.

4 kg

b.

2 kg

c.

8 kg

d.

0

Correct answer: a

Explosion-এ mass conserved ধরা হলে fragment masses-এর sum 4 kg।

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1776. MCQPractice set · Question 36

Perfectly inelastic collision-এ kinetic energy কী হয়?

a.

কমে

b.

conserved সবসময়

c.

বাড়ে সবসময়

d.

zero সবসময়

Correct answer: a

কিছু kinetic energy heat, sound বা deformation-এ যায়।

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1777. MCQPractice set · Question 37

Momentum conservation কি kinetic energy conservation নিশ্চিত করে?

a.

না

b.

হ্যাঁ সবসময়

c.

শুধু inelastic-এ

d.

শুধু rest-এ

Correct answer: a

Momentum conserved হলেও inelastic collision-এ kinetic energy কমতে পারে।

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1778. MCQPractice set · Question 38

Kinetic energy conserved হলে collision কী হতে পারে?

a.

elastic

b.

perfectly inelastic

c.

explosion only

d.

no interaction

Correct answer: a

Momentum-এর সঙ্গে kinetic energy conserved হলে ideal elastic collision।

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1779. MCQPractice set · Question 39

একটি 2 kg body 4 m/s এবং 2 kg body rest; perfectly inelastic final speed কত?

a.

1 m/s

b.

2 m/s

c.

4 m/s

d.

8 m/s

Correct answer: b

Initial p=8, total mass 4, তাই v=2 m/s।

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1780. MCQPractice set · Question 40

একটি 1 kg body 10 m/s east এবং 1 kg body 4 m/s west stick করলে final velocity কত?

a.

3 m/s east

b.

6 m/s east

c.

7 m/s west

d.

14 m/s

Correct answer: a

Net p=10−4=6; total mass 2, v=3 m/s east।

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