Irodov Problem 1.16

The position of the particle moving along the horizontal line in the Figure is given by -l₁ + v₁t and that of the particle moving in the vertical direction is given by -l₂ + v₂t. As shown in the figure the distance between the particle is given by,




The minimum can be obtained by differentiating d with respect to t and equating it to 0. Thus,









The distance for nearest approach can be obtained by substituting the value of t in the expression for d and obtained as,