Friday, March 8

Question in GIKI 2012 Test

Question :

Sum of two vectors A and B is equal to A. Difference of these two vectors is equal to 2A. If A=4 find the MAGNITUDE of vector B.
a)3√2
b)6√2
c)2√6
d)3√6

Question of GIKI test 2012.

 Solution:

In terms of rectangular components we can write:
A =√ A2x + A2y
B=√ B2x + B2y

Given:
A + B = A
it means 
 √( A2x + A2y ) +  √( B2x + B2y  ) =  4

Squaring Both sides, we get 
A2x + A2y  +  B2x + B2y   +  2√( A2x + A2y )( B2x + B2y  ) =  16       (equation i)

 Also
A-B = 2A
A-B = 8
√( A2x + A2y ) -  √( B2x + B2y  ) =  8

Squaring Both sides, we get 
A2x + A2y  +  B2x + B2y   -  2√( A2x + A2y )( B2x + B2y  ) =  64      (equation ii)

Adding equation i and ii we get 
2(  A2x + A2y  +  B2x + B2y  ) =  80
16 + B2x + B2y = 40
B2x + B2y = 24
B2 = 24
B = √24 = √4x6 = 2√6

at

10 comments:

  1. Ayesh20 March 2013 at 19:23

    what the hell was that? :O

    ReplyDelete
  2. Hassan Shahbaz21 March 2013 at 02:03

    @ayesha this was one of the question which was in test of GIKI last year :D

    ReplyDelete
  3. Ayesh25 March 2013 at 16:32

    and this is the hardest and worst thing one would ever wish to see, if the test goes this way, we shouldnt even bother about studying for it because its already a fail fail attempt

    ReplyDelete
  4. Hassan Shahbaz25 March 2013 at 23:50

    well in Giki u have to face the questions like these . It will be teh hardest test u'll ever see . The way to get through this test is to clear ur concepts..

    ReplyDelete
  5. Anonymous5 May 2013 at 00:52

    u substituted 16 but why ?
    in last part of the question ?

    ReplyDelete
  6. Hassan Shahbaz8 May 2013 at 11:49

    magnitude of A is equal to 16 .

    ReplyDelete
  7. Anonymous29 June 2013 at 19:00

    Awesome site you have here but I was curious if you knew
    of any forums that cover the same topics talked about here?
    I'd really like to be a [] part of community where I can get opinions from other experienced people that share the same interest. If you have any recommendations, please let me know. Thank you!

    ReplyDelete
  8. Anonymous2 July 2013 at 13:36

    WE are supposed solve it in a minute?

    ReplyDelete
  9. Anonymous2 July 2013 at 13:37

    we are supposed to solve it in a minute?

    ReplyDelete
  10. Hassan Shahbaz3 July 2013 at 10:39

    I have found a short method for this as well. Will add that too.

    ReplyDelete