Archaic projectile points from the Andean Altiplano exhibit a curious trend of increasing size over time, in contrast to well-documented reduction throughout North America. Although number hypotheses exist account for decreasing projectile-point size, there are currently no explicit explanations size. We consider several and interrogate two techno-economic hypotheses. posit that point compensat...

The axisymmetric steady state deformations of an infinite cylindrical rod made of a rigid/perfectly plastic material and striking a known cavity in a rigid target are analyzed by the finite element method. The contact between the deforming rod and the target surface is assumed to be smooth. It is found that the axial force experienced by the rod depends strongly upon the square of its speed. Re...

The penetration of a projectile into warship broadside liquid cabin is usually non-ideal process. To explore the protective effects large against rod projectiles and to provide reference for design new structures, ballistic impact tests penetrating at different attack angles were carried out. Combined with numerical calculation, angle on water entry characteristics as well their failure modes s...

The steel ball will be launched horizontally by being released at a certain height on the ramp. It will then fall to the floor and make a mark on the landing paper. The horizontal distance from take-off to landing, x, is proportional to the initial horizontal velocity, v0, of the ball. The distance, x, can be measured with the meter stick. By using the SALT®, photogate and computer, the time ca...

Dark material on Vesta may consist of carbonaceous chondrite-like material delivered by impact events. This study uses hypervelocity impact experiments to assess the viability of the impact delivery hypothesis. Experiments reveal that impact events deliver significant fractions of the projectile to the target during impacts at average vestan speeds. Hence, dark material can plausibly be deliver...

The purpose of this study was to compare traditional and swing blocking techniques on center of mass (COM) projectile motion and effective blocking area in nine healthy Division I female volleyball players. Two high-definition (1080 p) video cameras (60 Hz) were used to collect two-dimensional variables from two separate views. One was placed perpendicular to the plane of the net and the other ...

Introduction: A projectile is a body in free fall that is subject only to the forces of gravity (9.81ms⎯2) and air resistance. An object must be dropped from a height, thrown vertically upwards or thrown at an angle to be considered a projectile. The path followed by a projectile is known as a trajectory. If gravity were not present, a projectile would travel in a constant straight line. Howeve...

Ion irradiation of nanoparticles leads to enhanced sputter yields if the nanoparticle size is of the order of the ion penetration depth. While this feature is reasonably well understood for collision-cascade sputtering, we explore it in the regime of collision-spike sputtering using molecular-dynamics simulation. For the particular case of 200-keV Xe bombardment of Au particles, we show that co...