Miscellaneous

ADDED Q9,Q10,[ Q8) .....by avinav ]don't have the answers so can't confirm

Q1 )
The max. resultant of two forces is P and the minimum resultant is Q . If the two forces are at right angles then resultant is ..........

Q2) L.P.G mainly contains
a) ethyne b) methane c) butane d) ethane

Q3) the enzymes which converts proteins into amino acids during digestion
a) protienases b) lipases c) amylases d) adenine

Q4) If \vec{a_{1}} and \vec{a_{2}} are two non collinear vectors and if | \vec{a_{1}} + | = √3 then the value of
( - \vec{a_{2}}) ( 2\vec{a_{1}}+\vec{a_{2}} ) is ....
a) 2 b) 3/2 c) 1/2 d) 1

edited : i have edited collinear as non-collinear , earlier i rongly typed as collinear [2][2] SRY

Q5) which of the following optical components forms a perfect image free of abberration ?
a) Plane mirror b) spherical mirror C) spherical lens D) cylindrical lens

Q6) the absolute value of \left(\frac{2Z-8i}{3\bar{Z}+12i} \right)^{3} is ...

Q7) here solid lines are crests and dashed r trough
The diagram shows two sources A and B vibrating in phase in the same uniform medium and producing circular wavefronts. Which phenomenon occurs at Point P ?

a) destructive inteference b) constructive interference c) reflection d) refraction
[ ( Q8) mentioned below by avinav already ]

Q9) Glass is a
a) polymeric mixture b) micro crystalline solid c) Super cooled liquid d) gel
i feel like c am i rite ??

Q10) which of the following culd act as a propellant for rocket
a) liquid N2 + liquid O2 b) liquid H2 + liquid N2 c) liquid H2 + liquid argon
d) liquid H2 + liquid O2 i feel like it's( a )am i rite ??

49 Answers

1
harsh jindal ·

explain subho how can be
2A2+b2 -3ABcosB
it should be
2A2-b2-ABcosB

1
rahul nair ·

8) C- increase

49
Subhomoy Bakshi ·

they increase whatever the case may be!!

49
Subhomoy Bakshi ·

the distance b/w the centres + shortest distance b/w circumference..all will increase!! if heated..

[1][1]

23
qwerty ·

nishant sir , if a1 and a2 are non collinear , how can u take the case a1 = a2

1
Avinav Prakash ·

yA ITS RITE...

I HOPE THE ABOVE Q HAS SOLVD ALL THE DOUBTS FROM OUR MINDS....IF AT ALL THERE WERE ANY

49
Subhomoy Bakshi ·

@#2 ans is butane...

actually...the normal we get has 60% propane + 40% butane!! [1][1]

23
qwerty ·

Q8 ) the expansion due to heat is similar to virtual expansion of an image when we zoom into it .......

i think c , wen we will zoom into the image , we wont expect the distance to decrease, but it will increase

49
Subhomoy Bakshi ·

kudos!!!

49
Subhomoy Bakshi ·

Q 6))

let Z=x+iy
Z=x-iy

|(2Z-8i3Z+12i)3|
=|2Z-8i3Z+12i|3

=|2x+i(2y-8)3x-i(3y-12)|3

=|2[x+(y-4)i]3[x-(y-4)i]|3

=827.|[x+(y-4)i][x-(y-4)i]|3

let z=x+(y-4)i
z=x-(y-4)i

so, given exp=827.|zz|3

=827.(|z||z|)3

=827.........hence the answer

P.S.: |z|=|z|

49
Subhomoy Bakshi ·

questions completed 1, 2 , 3, 5, 6, 8!!

left,, 4 and 7

49
Subhomoy Bakshi ·

for question 4,

the simplified form comes to this

given A2+B2+2AB cosθ=3

find, 2A2+B2-3ABcosθ

49
Subhomoy Bakshi ·

i had replaced a1 by A and a2 by B for easy typing..[1][1]

1
Avinav Prakash ·


Q8>
2 holes of diameter d1 and d2 are cut in metal sheet...if teh sheet is heatd the distance b/w the holes will
a)remain constant
b) decrease
c)increase
d)may either increase or decrese depending on the ratio d1/d2.

49
Subhomoy Bakshi ·

oops....[2][2]...u are right...calculations mistake...

it is indeed 2A2-B2-ABcosθ=A2+B2+2abcosθ-2B2-3Acosθ=3-2B2-3ABcosθ

now this leads us to nowhere...[2][2][2][2]

1
Manmay kumar Mohanty ·

Q7) i got it as constructive inteference since crests are formed due to constructive interference and point P lies on a crest indicated by bold lines.

THNNKS ALL FOR UR VAluable HELP.....

[1][1]

between added Q9) and Q10) please anyone confirm me[1]

1
Avinav Prakash ·

9) ans shud be (A)..as nitrous oxide is formd
10) super cooled liquid perhaps..
wiki says glass is not crystalised

1
Manmay kumar Mohanty ·

thnk U ..[1]

29
govind ·

For 9th Super cooled liquid is correct but for 10th i think it shud be D

3
rocky ·

yes govind u are correct.....10 ans is d

1
Arka Halder ·

Ya 9 c. glass is a supercooled liquid as a consequence of which windows in old buildings are thicker at their bases
10 d

62
Lokesh Verma ·

@querty.. even i was surprised by what i had done..

but lets take two vectors a1 and a2....

Let a1 be very small.. and a2 be very close to root (3)

in the other case take the reverse...

I do not intend you to take a1 to be collinear to a2 (it is just a small vector)

Then what we have is that this dot product given above gives two different results... So I presume that the question is wrong!

1
Manmay kumar Mohanty ·

nishant bhaiya please maaf kar do mujhe becoz i edited the question since it was non-collinear not collinear islye.
SRY for inconvenience [2]

62
Lokesh Verma ·

it is ok manmay :)

1
Manmay kumar Mohanty ·

but bhaiya please solution to that question please bhaiya........ U know math main ek hi chapter hai jo mujhe pasand nahin VECTORS ............ please help me bhaiya please solution post kardijiye na [2]

1
archana anand ·

Q3 luks biology to me coz i never studied biomolecules:p

1
Manmay kumar Mohanty ·

thnks bhaiya [1]

1
pranav ·

2)butane hai kya?

1
Manmay kumar Mohanty ·

answer given nahin hai..........[2]

1
pranav ·

butane hi hai,....!

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