Play with bomb parameters

Changing one parameter in the Stromboli bomb trajectory applet, and leaving all others constant, will give you interesting insights into the effects of physical variables. Try to answers questions such as:

Does size matter?

Use a reasonable launch angle (such as 45°) and launch velocity (such as 100 m/s). Then set bomb diameters to 10, 30, 100, 300 centimetres. If you switch off the effect of air resistance, all bombs will follow the same trajectory. In the real world there obviously is air resistance. It will affect bigger bombs less as their cross section, in relation to their volume and, therefore, mass is smaller. Consequently, during big explosions, far flying bombs will be sorted according to their sizes, with only the biggest bombs reaching the furthest distances from the crater.

Bombs from a unusually strong eruption which fell on Pizzo on 16. October 1993 illustrate the wide range of sizes: The smaller ones on the left have diameters in the order of 20 cm, the bigger one, after impacting on the ground, is nearly 2 meters long; however, in flight it might have been more spherical and, therefore, more compact.

How does the launch angle affect distances reached?

In a vacuum, and on a horizontal ground, the largest distances are reached by a ballistic projectile when launched at an angle of 45°. If air resistance is taken in account or if the terrain is not flat, other angles, usually somewhat smaller than 45°. Other obvious parameters to vary are the launch direction (some places along the coast are much further from the crater than others...), or the starting velocity.

During this small eruption from NE crater bombs are ejected at a large variety of launch angles from 90° (vertical) to perhaps as little as 40°. Note the bomb on the right which travelled furthest due to an "ideal" launch angle.