Two particles are projected with speed 4 m/s and 3 m/s simultaneously from same point as shown in the figure. Then:

So, velocity of first particle        =3cos⁡37∘i^+3sin⁡37∘j^=125i^+95j^Velocity of second particle       =4cos⁡53∘i^+4sin⁡53∘j^=125i^+165j^So, relative horizontal velocity is zero. So their relative velocity is vertical only. Since both particles are moving under gravity so that relative acceleration is zero.Their relative velocity =165−95=75=1.4m/s