Two paper discs are mounted on a rotating vertical shaft. The shaft rotates with a constant angular speed `omega` and the separation between the discs is H. A bullet is fired vertically up so that it pierces through the two discs. It creates holes H1 and H2 in the lower and the upper discs. The angular separation between the two holes (measured with respect to the shaft axis) is `theta`. Find the speed (v) of the bullet. Assume that the speed of the bullet does not change while travelling through distance H and that the discs do not complete even one revolution in the interval the bullet pierces through them.

Answer

`v = (omega H)/(theta)`