Calculate the time difference

Question

The two particle  are oscillating along two close  parallel straight line in opposite  direction towards the mean position The time taken by the particle  X=0 to x=A/2 is T/12 and x=A to x=A/2 is T/6. Then calculate the time difference.

Ans-T/3

Comments

I had uploaded the solution . Just only explain me why it  is added T/6 +T/6 =T/3  . Why it  not had taken the difference  of the time calculated  above (T /6 -T/12)

---

Can anyone  answer it?  It is urgent.

Answer 1

Time taken by the  first particle is   t/12 and second one is t/6 but first one has to reaches the mid point   ( that point they cross each other)  therefore  first particle will     crossed  before  attaining  the t/12 time .   ( both meet at t/6 time. )That's the REASON  why  it is  not considered   t/12 and used the value t/6.

Both  moving in opposite  direction , so   one particle  should  be-t/6)

Next,  time difference t/6-(-t/6) =t/3