and secondary cracks are present. ](crack/90_100_0.01000.ps "fig:"){width="30.00000%"}   ![\[snapshot\] Final reassembled states of the break-up process of a disc of radius $30$ cm at different impact velocities dropped on a hard frictionless plate. (a) $v_0 = 100$ cm/sec. The cone is not fully developed and only few oblique cracks are present. (b) $v_0 = 200$ cm/sec. More oblique cracks develop and travel a greater distance. (c) $v_0 = 600$ cm/sec. Both oblique cracks and secondary cracks are present. ](crack/90_200_0.01000.ps "fig:"){width="30.00000%"}   ![\[snapshot\] Final reassembled states of the break-up process of a disc of radius $30$ cm at different impact velocities dropped on a hard frictionless plate. (a) $v_0 = 100$ cm/sec. The cone is not fully developed and only few oblique cracks are present. (b) $v_0 = 200$ cm/sec. More oblique cracks develop and travel a greater distance. (c) $v_0 = 600$ cm/sec. Both oblique cracks and secondary cracks are present. ](crack/90_600_0.01000.ps "fig:"){width="30.00000%"}
                                                                                                                                                                                                                                             (a)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       (b)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       (c)
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Crack patterns obtained in the final state of oblique impacts at impact angles $75^{\circ}, 60^{\circ}$ and $45^{\circ}$ are compared in Fig. \[snap2\]. It is important to emphasize that in our calculations the friction between the target plate and the circular disc is completely 