Related papers: A Modular Supersonic Ping Pong Gun
We perform large-scale molecular dynamics simulations to study heated granular fluids in three dimensions. Granular particles dissipate their kinetic energy due to solid frictional interaction with other particles. The velocity of each…
Spinning objects which move through air or liquids experience a Magnus force. This effect is commonly exploited in ball sports but also of considerable importance for applications and fundamental science. Opposed to large objects where…
We present the experimental realization of a long-lived superfluid flow of a quantum gas rotating in an anharmonic potential, sustained by its own angular momentum. The gas is set into motion by rotating an elliptical deformation of the…
The pressure wave emitted from the air gun contains many frequencies, among which the low-frequency waves are desirable for exploration and imaging, while the high-frequency waves need to be suppressed as they are harmful to marine species.…
For centuries, bubbles have fascinated artists, engineers, and scientists alike. In spite of century-long research on them, new and often surprising bubble phenomena, features, and applications keep popping up. In this paper I sketch my…
A classic problem of the motion of a projectile thrown at an angle to the horizon in a medium with a quadratic resistance law is studied. An approximate analytical solution of the equations of projectile motion is presented, which has a…
A cylindrical system is proposed that will store magnetic energy in a localized azimuthal field that can then be quickly released on Alfvenic timescales, accompanied by the formation of a flowing Z-pinch plasma. The magnetized plasma is MHD…
An approximate vacuum wave functional $\Psi_0$ is proposed for $2+1$-dimensional Yang-Mills theories. Using $\Psi_0$, one can compute the $0^{++}$ glueball mass $M_G$ in terms of the string tension. By using the idea of dimensional…
It can be a challenge to come up with simple demonstrations of circular motion and conservation of energy. One such demonstration consists of a large exercise ball, off of which a small solid or hollow ball is rolled. The small balls are…
We report an ulsrasonic measurements of density and bulk modulus of propylene glycol at room temperature and at the temperature of liquid nitrogen combined with molecular dynamics simulations with two different force fields. We find that…
Any gravitating mass traversing a relatively sparse gas experiences a retarding force created by its disturbance of the surrounding medium. In a previous contribution (Lee & Stahler 2011), we determined this dynamical friction force when…
Beams of atoms and molecules are stalwart tools for spectroscopy and studies of collisional processes. The supersonic expansion technique can create cold beams of many species of atoms and molecules. However, the resulting beam is typically…
This article describes a simple method for using a PC soundcard to accurately measure bullet velocity. The method involves placing the microphone within a foot of the muzzle and firing at a steel target between 50 and 100 yards away. The…
We report an innovative high pressure method combining the diamond anvil cell device with the technique of picosecond ultrasonics. Such an approach allows to accurately measure sound velocity and attenuation of solids and liquids under…
We report an experimental study of particle kinematics in a 3-dimensional system of inelastic spheres fluidized by intense vibration. The motion of particles in the interior of the medium is tracked by high speed video imaging, yielding a…
The particles on demand (PonD) method is a new kinetic theory model that allows for simulation of high speed compressible flows. While standard Lattice-Boltzmann is limited by a fixed reference frame, significantly reducing the range of…
Putting several hard balls into a two-dimensional bowl can form a very basic two-dimensional model of hard-ball system. When the two-dimensional bowl has a parallel-rotation at a uniform speed around a center, when the number of balls is…
A novel method for doping plasmas in pulsed-power experiments with gaseous elements has been developed. A fast gas valve, a nozzle, and a skimmer are used to generate an ultrasonic gas beam that is injected into a planar-geometry…
We report experimental results on the parameters, structure, and evolution of high-Mach-number (M) argon plasma jets formed and launched by a pulsed-power-driven railgun. The nominal initial average jet parameters in the data set analyzed…
We consider systems of "pinned balls," i.e., balls that have fixed positions and pseudo-velocities. Pseudo-velocities change according to the same rules as those for velocities of totally elastic collisions between moving balls. The times…