AITS phaltu question.

a rod of length 2m moves in horizontal x-y plane. at any instant end 'a' of the rod is at the origin and has velocity V1 (see fig.). the other end B at the same instant is moving with velocity V2 (see fig.). the rod makes an angle of 30 deg with the x-axis at this instant.

(a) magnitude of angular velocity of the rod ???

>> 1 rad/s.
>> √3 rad/s.
>> √3/2 rad/s.
>> 1/2 rad/s.

N.B. : mujhe yeh question hi samajh me nahi aya :(

12 Answers

62
Lokesh Verma ·

u need to use that the relative velocity along the rod is 0

1
Rohan Ghosh ·

this is an easy one(but in the exam due to different data in question and in figure i didnt take the risk)
first of all the velocity along the rod's length is zero(as its length remains constant)

hence let the rod be r->

and both the velocities be a-> and b->

then just apply
r->.a-> and r->.b->

and from there find the velocities along the rod (which is r->.a->/2 and r->.b->/2)

equating them

2√3+Vy=3√3+6
Vy=6-√3

now find the perpendicular velocities at both the ends

and then find the instantaneous centre of rotation and apply wx=Va or Vb

33
Abhishek Priyam ·

Most probably they say in FIITJEE... this question was cancelled...

As far as this question is concerned The length of rod cannot increase thats the trick...

9
Celestine preetham ·

vel of end2 wrt 1 is 1i + 6-V j
now its perpendicular to rod

ωLsin30 = 1

ω=1

9
Celestine preetham ·

can u please tell me wats phaltu!!!!!!

i dont know hindi

62
Lokesh Verma ·

phaltu = waste

1
varun.tinkle ·

can anyone expain to me celestines working

i think its some kind of shortcut

1
Arshad ~Died~ ·

this question was wrong and was cancelled last year.....

21
eragon24 _Retired ·

yeah i guess it was cancelled.....tats why i guess everyone got more marks then expected in PT1 last year.....those 12 marks were given as a gift[3]

23
qwerty ·

lolz..rofl

1
Kartik Sondhi ·

I think the answer is 1 (a)

1
Arshad ~Died~ ·

@kartik
see post no. 9
lolz

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