Three particles `A,B` and `C` and situated at the vertices of an equilateral triangle `ABC` of side of length `l` at time `t=0`,Each of the particles move with constant speed `u`. A always has its velocity along `AB, B` along `BC` and `C` along `CA`.

Options

A. 2D/3V
B. 5D/7V
C. 6D/10V
D. 7D/9V

Answer

A

Explanation

If we consider the `DeltaPQR`, velocity of P along PQ is `V= V_(Q)` along OR. It.s component along QP is `V cos 60^(@) = V//2`. So separation PQ decreases at the rate of `V+ (V//2) = 3v//2`. Time taken will be `(D)/((3V//2)) = (2D)/(3V)`