question_answer

Initially the spring is undeformed. Now the force \[F\] is applied to \[B\] as shown in the figure. When the displacement of \[B\] w.r.t. \[A\] is x towards right in some time then the relative acceleration of \[B\] w.r.t. \[A\] at that moment is

A) \[\frac{F}{2m}\]                       

B) \[\frac{F-kx}{m}\]

C) \[\frac{F-2kx}{m}\]      

D) None of these

Correct Answer: C

Solution :

[c] \[F-kx=mb\] and \[kx=ma\] Hence \[m(b-a)=F-2kx\] or \[b-a=\frac{F-2kx}{m}\]