Four particles `A, B, C and D` are situated at the cornerst of a square `ABCD` of side `a at t-0`. Each of particles moves with constant speed (v). A always has its velocity along `AB, B` along `BC, C` along `CB~ and D` along `DA`. At what time will these particles meet each other ?

Explanation

The motion of four particles `A, B, C` and D` is as shown in Fig. 2 (a) .31` by soled curved lines. Theey will be meeting at the centre (O) of the square `ABCD`. It means, the particle at (A) will be comerting a displacement `A O` before meeting the other partiles . The velcoty ofthe particle at `A along AO`
``=v cos 45^(0) = v/(sqrt2)`
`cos 45 ^(0) =AE//AO`
or `AO =(AE)/(cos 45^(0)) =(a//2)/(1//sqrt2) =a/(sqrt2)`
.
The time take by particle at (A) to go from (A) to (O)`
`=(AO)/(v cos 45^(0)) =(a// sqrt2)/(v (1// sqer2)) =a/v`.