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A-body-is-at-rest-at-x-0-At-t-0-it-starts-moving-in-the-positive-x-direction-with-a-constant-acceleration-At-the-same-instant-another-body-passes-through-x-0-moving-in-the-positive-x-directio




Question Number 16645 by Tinkutara last updated on 24/Jun/17
A body is at rest at x = 0. At t = 0, it  starts moving in the positive x-direction  with a constant acceleration. At the  same instant another body passes  through x = 0 moving in the positive  x-direction with a constant speed. The  position of the first body is given by  x_1 (t) after time ′t′ and that of the  second body by x_2 (t) after the same  time interval. Which of the following  graphs correctly describes (x_1  − x_2 ) as  a function of time ′t′?
Abodyisatrestatx=0.Att=0,itstartsmovinginthepositivexdirectionwithaconstantacceleration.Atthesameinstantanotherbodypassesthroughx=0movinginthepositivexdirectionwithaconstantspeed.Thepositionofthefirstbodyisgivenbyx1(t)aftertimetandthatofthesecondbodybyx2(t)afterthesametimeinterval.Whichofthefollowinggraphscorrectlydescribes(x1x2)asafunctionoftimet?
Commented by Tinkutara last updated on 24/Jun/17
Answered by ajfour last updated on 24/Jun/17
only a little time after t=0   x_2  will be greater than x_1  since  the first body will have gained  only a little velocity while the  second body had an initial  velocity of you, that is, if time  has not progressed by much   x_1 −x_2 < 0 .And after sufficient  time first body (because it is accelerated)  continues gaining velocity, surpases  velocity u and then overtakes the  second (x_1 =x_2 ) and thereafter their separation  goes increasing[ (x_1 −x_2  ) increases].  such is represented only in (2) .
onlyalittletimeaftert=0x2willbegreaterthanx1sincethefirstbodywillhavegainedonlyalittlevelocitywhilethesecondbodyhadaninitialvelocityofyou,thatis,iftimehasnotprogressedbymuchx1x2<0.Andaftersufficienttimefirstbody(becauseitisaccelerated)continuesgainingvelocity,surpasesvelocityuandthenovertakesthesecond(x1=x2)andthereaftertheirseparationgoesincreasing[(x1x2)increases].suchisrepresentedonlyin(2).
Commented by Tinkutara last updated on 24/Jun/17
Thanks Sir!
ThanksSir!

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