মেকানিক্যাল ইঞ্জিনিয়ারিং

1711. MCQPractice set · Question 74

COM-এর acceleration কোন force দিয়ে নির্ধারিত?

a.

net external force

b.

internal force only

c.

friction inside only

d.

mass distribution only

Correct answer: a

M a_COM=ΣF_external।

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1712. MCQPractice set · Question 75

Internal explosion-এ isolated system-এর COM কী করে?

a.

আগের uniform motion বজায় রাখে

b.

হঠাৎ accelerate করে

c.

rest-এ যায়

d.

mass হারায়

Correct answer: a

Internal forces total COM momentum পরিবর্তন করতে পারে না।

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1713. MCQPractice set · Question 76

Momentum-এর vector nature কী কারণে?

a.

velocity vector

b.

mass scalar নয়

c.

force scalar

d.

unit vector only

Correct answer: a

p=mv এবং m scalar, তাই p-এর direction v-এর direction।

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1714. MCQPractice set · Question 77

দুটি momentum opposite equal হলে total momentum কত?

a.

0

b.

2p

c.

p²

d.

p/2

Correct answer: a

Equal opposite vectors cancel করে।

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1715. MCQPractice set · Question 78

একটি 1 kg body 4 m/s east এবং 1 kg body 4 m/s west-এ চললে total momentum কী?

a.

0

b.

4 kg·m/s east

c.

8 kg·m/s

d.

16 kg·m/s

Correct answer: a

Momentum equal opposite, তাই total zero।

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1716. MCQPractice set · Question 79

দুই body stick করলে final velocity নির্ণয়ে কোন conservation ব্যবহার হয়?

a.

momentum conservation

b.

kinetic energy conservation always

c.

force conservation

d.

power conservation

Correct answer: a

Perfectly inelastic collision-এ momentum conserved, kinetic energy নয়।

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1717. MCQPractice set · Question 80

1 kg body 6 m/s-এ এবং 2 kg body rest-এ; তারা stick করলে final speed কত?

a.

1 m/s

b.

2 m/s

c.

3 m/s

d.

6 m/s

Correct answer: b

6=(1+2)v, তাই v=2 m/s।

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1718. MCQPractice set · Question 81

Elastic collision-এ coefficient of restitution কত?

a.

1

b.

0

c.

−1

d.

2

Correct answer: a

Perfectly elastic collision-এ e=1।

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1719. MCQPractice set · Question 82

Perfectly inelastic collision-এ coefficient of restitution কত?

a.

0

b.

1

c.

−1

d.

infinite

Correct answer: a

দুই body একই velocity-তে চলে, relative separation speed zero; e=0।

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1720. MCQPractice set · Question 83

Collision-এ kinetic energy loss কোন collision-এ maximum?

a.

perfectly inelastic

b.

perfectly elastic

c.

no collision

d.

elastic only

Correct answer: a

Perfectly inelastic collision-এ bodies stick করে এবং kinetic energy loss maximum।

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