The forces involved in the motion of objects within noninertial reference frames are challenging concepts for introductory and advanced mechanics students. Furthermore, students often struggle to predict the trajectories of an object due to these fictitious forces. While most students encounter noninertial reference frames daily, students often spend most of their physics coursework analyzing situations in which the Coriolis and centrifugal forces are negligible. We developed an interactive and freely accessible simulation of a rotating turntable apparatus that aims to improve understanding of the motion of objects in noninertial reference frames.
At Cal Poly Humboldt, undergraduate researchers and faculty have constructed a torsion-pendulum experiment that seeks to measure gravitational interactions below test mass separations of 100 microns. The aim of this experiment is to look for deviations in the weak equivalence principle (WEP) and inverse-square law (ISL). The scale at which this experiment operates is within an untested range at the submillimeter scale. This apparatus’s torsion pendulum consists of equal masses with differing materials arranged as a composition dipole. The twist of this configuration is measured as an attractor mass oscillates in a parallel-plate arrangement nearby. The oscillation creates a time-dependent torque on the pendulum which can be studied for deviations in the WEP and ISL. At present, an active leveling scheme has been implemented to mediate the apparatus’s long-term tilt variations. This scheme has been optimized through the use of a power supply and proportional-integral-derivative (PID) loop that mitigates the variations in tilt by applying a voltage to a resistor attached to one of the apparatus legs. The applied voltage causes thermal expansion of the apparatus leg support structure, thus correcting and modulating the tilt of this experiment.
In this work, we used Mössbauer spectroscopy and magnetometry at room temperature to investigate the magnetic properties of four different iron oxide samples (α-FeOOH, γ-Fe2O3, or Fe3O4 and α-Fe2O3) before and after annealing at 1000°C for one hour. We found that after annealing, all four samples exhibited the same properties as hematite (α-Fe2O3). These results show that the iron oxides in this study underwent phase transformations from an initial phase of either α-FeOOH, γ-Fe2O3, or Fe3O4 to a single final phase of α-Fe2O3.
According to the classical adhesion explanation for the phenomenon of friction, the friction coefficient between two surfaces is defined as the ratio between the horizontal friction force exerted on each surface and the perpendicular normal force between each surface. There is a paucity of published investigations into the relationship between the contact temperature of a polymer-nonpolymer physical interface and the resultant static friction coefficient at varying temperatures. This study investigates the relationship between temperature and the static friction coefficients of five recyclable thermoplastic polymers in polymer-aluminum interfaces across a range of temperatures. The results demonstrate a generalizable relationship between the static friction coefficient and the contact temperature of polymer-aluminum interfaces which corresponds to polymer-specific phase-change temperatures.
It is well documented that a significant number of high school physics teachers around the country have little to no background in the discipline, which can result in reduced student learning in the classroom. The Mitchell Institute Physics Enhancement Program (MIPEP) was founded in 2012 to address this problem by targeting out-of-field high school physics teachers. MIPEP participants work with university faculty and master teachers over a two-week period during June each summer, focusing on both subject comprehension and pedagogy for implementation. Participant pre- and postprogram content knowledge and confidence were measured using an assessment compiled of questions from mechanics, electricity and magnetism, optics, and modern physics. We observed statistically significant improvement in both physics knowledge and confidence over the course of the program. A detailed analysis of the 2021 cohort showed that a majority of participants grew in knowledge and confidence for every topic covered. The data presented may encourage other institutions to implement similar programs.
Through the formalism of the partition function, perturbations on the classical ideal gas are considered. The perturbations include externally applied fields and rotating the reference frame. The rotating reference frame offers a stark pedagogical opportunity to show why statistical mechanics requires canonical momentum in contrast to mv momentum.
Static light scattering (SLS) is a powerful, noninvasive experimental method that yields the molecular weight (average molecular weight, Mw), the size (radius of gyration, Rg), and the interactions between the scatters (the second virial coefficient, A2). However, proper SLS measurements require determination of the specific refractive index increment (dn/dc) for the samples studied. While tables of dn/dc values are available for various substances, they are not generally available for microgel particles, which in our case are crosslinked chains of an amphiphilic polymer. This paper is focused on measuring dn/dc for microgel samples of varying crosslinking concentrations. Microgel dn/dc values were found to be different from the value of the parent polymer given in literature and found to have a temperature dependence as well as a crosslinker concentration dependence at higher crosslinker concentrations. Using the measured values of microgel dn/dc instead of tabulated parent polymer values on estimates of microgel Mw, Rg, and A2 highlights the importance of direct dn/dc measurements for samples studied by SLS.
Today’s high-tech society creates a pressing need for advanced medical prosthetics and industrial grippers. However, as technological advancements continue to be incorporated, a gap is created by the quality–cost ratio associated with using technologically advanced solutions. For example, many open-source prosthetics provide relatively inexpensive devices, but they often sacrifice the ability to grip irregularly shaped or smooth objects. For instance, doorknobs are difficult to grip using the typical hard robotics approach but can be gripped using soft robotic techniques. Prior work with soft robotics successfully used compressed air and a small granular material (coffee grounds) to build a gripper that can hold various objects. However, the use of compressed air makes these devices relatively slow, and the need for an air compressor limits the applicability of this design. Our primary goal was to explore the feasibility of a soft robotic approach that utilizes ferromagnetic granular materials to grip an object via the granular jamming transition that is induced with an external magnetic field. The granular material is placed inside flexible membranes made of polyisoprene, wherein the granular materials can go from a more relaxed state to a more rigid state depending on the strength of the magnetic field. The flexible membrane also allows the object to be held and then return to its original state when released. A solenoid provides a magnetic field that is easily turned on and off to jam and unjam the magnetic granular material and thus allows us to hold an object in place without the use of compressed air. In searching for a magnetic granular material, we found that iron filings work well, as they easily conform to the shape of the object. We have observed success in holding and releasing several smooth knobs as well as more angular shapes. This work will further the development of a low-cost but high- functioning universal gripper with applications in prosthetics and pick-and-place devices, as well as a multitude of industrial applications.
Two charged particle detectors were built using resources available from the Cosmic Watch program. Along with other atmospheric trends, the cosmic ray rate as a function of altitude was measured to heights above 20 km via the use of high-altitude balloon launches with the detectors as part of the payload. Atmospheric data, verification of the detectors, and cosmic ray rates will be discussed.
New York state is reducing its carbon footprint through the Community Leadership and Climate Protection Act. One important target is methane, a potent greenhouse gas that contributes 35% of the state’s CO2-equivalent emissions.1 Here we present the results of mobile observations conducted to better identify and quantify emissions of methane in central New York. We discovered a modest source of methane following numerous visits to a mining operation. During repeated visits the facility produced two distinct plumes with ethane and methane ratios of 0.010 and 0.007, which differ from local natural gas infrastructure. Using a Gaussian plume approach, we estimate the emission flux to be 70−100 kg/h. Additional observations are required to better refine our estimate.
The 3He(n,p) process is excellent for neutron detection between thermal and ∼4 MeV because of the high cross section and near-complete energy transfer from the neutron to the proton. This process is typically used in gaseous forms with ionization readout detectors. Here we study the response of a liquid 3He neutron detector with a scintillation readout. We anticipate an efficiency boost of around a factor of 64 compared to 10-atm gaseous detectors, given similar detector volumes.
We present an overview of quantum computing, including relevant physics, processes, and applications. This includes describing the basic framework of the quantum bit, which serves as the foundation for the rest of this paper. We found rapid developments in quantum computing, which will have important consequences for future applications in scientific fields.
We present an overview of quantum computing, including relevant physics, processes, and applications. This includes describing the basic framework of the quantum bit, which serves as the foundation for the rest of this paper. We found rapid developments in quantum computing, which will have important consequences for future applications in scientific fields.
We present neutral hydrogen observations of the plane of the Milky Way galaxy between 0° < l < 80° galactic longitude on the 20-meter telescope at the Green Bank Observatory. These radio spectroscopic signatures returned the 21-cm line of neutral hydrogen at various offsets due to the Doppler shift. By calculating orbital speeds relative to the galactic center, velocity was plotted against radial distance to map the rotation curve of the Milky Way galaxy. The distribution of luminous matter suggests that orbital velocity should fall off at large distances, but empirical observations show otherwise. An abundance of mass which cannot be detected is responsible for this phenomenon, known as dark matter. Although its nature is not understood, dark matter is easily observed indirectly by galactic rotation curves. Our observations confirm that the velocity of the Milky Way’s disk is fairly constant even at large distances from the center of our galaxy, Sagittarius A*.
Brown dwarfs in the L-T spectral class transition commonly experience photometric variability due to the active formation/dissipation of clouds that rotate in and out of our view. Measurements of these photometric oscillations, such as their frequency and amplitude, may help constrain the physical parameters of observed brown dwarfs through their associations with aspects such as rotational period and surface temperature. However, measurements of these oscillations and their significance are obscured by the inclination angle of observed brown dwarfs relative to us. By creating a simplistic model of 2D cloud formation on the surface of a toy model brown dwarf, this paper aims to further explore the relationship between oscillation amplitude and inclination angle for cloudy brown dwarfs and finds agreement with the correlation found observationally between the two factors in Vos et al., 2017.
Exotic behavior of linearly dispersed electronic bands near the Fermi level implies advanced physical properties in a material. In this paper, we present an ab initio study of the electronic properties of IrGa and RhGa, with and without spin-orbit interaction, using first-principles calculations. Linearly dispersed band crossings, reminiscent of topological semimetallic band structures, were identified near the Fermi energy. These include type-I and type-II Dirac points and nodal lines. By applying compressive and tensile stress to the lattice along x, y, and z, the response to the band structure near the Fermi level has been studied.
We consider a system consisting of a qubit and a microwave transmission line that are coupled by a capacitor which, in turn, is modulated sinusoidally. The Unruh effect is the simultaneous production from vacuum of a pair of photons, one in the qubit and the other in the cavity. The dynamical Casimir effect is the production from vacuum of a pair of photons in the cavity. We analyze this qubit–cavity system and show that the system can be viewed as a pair of coupled quantum-mechanical oscillators and that both the Unruh effect and the dynamical Casimir effect are resonances of this coupled oscillator system. For the case where the cavity supports two propagating modes, in addition to the Unruh and dynamical Casimir effect at each of the supported modes, we predict a “paired Casimir effect,” where one photon is emitted in the cavity in each of two allowed modes, at the appropriate driving frequency. We also calculate analytical approximations to the driving frequencies for all three effects.
This study focuses on the dielectric properties of 21.9-nm spherical zinc oxide (ZnO) nanoparticles (NPs) at room temperature, as a dry powder and suspended in a liquid. Impedance spectra in the frequency range of 100 Hz to 5.1 MHz were used to investigate the frequency-dependent dielectric properties of ZnO NPs. The commercially available ZnO NPs used in this study were suspended in variable volume fractions up to ∼1% in deionized (DI) water and unrefined organic coconut oil and subjected to three sonication conditions: no sonication (NS), 1 hour of bath sonication (BS), and 1 hour of bath sonication followed by probe sonication throughout the experiment (CS, “concurrent sonication”) to determine sonication dependence. Small volumes of the resulting suspension were injected sequentially into a dielectric cell for measuring frequency response. Dry particle tests were conducted similarly. Impedance data suggests that the dielectric behavior of ZnO NPs in a liquid suspension is highly dependent on sonication before and during the test and exhibited a strong dependence of dipole with the polarity of the liquid at low frequencies. In addition, a higher dielectric constant of ZnO NPs was observed when the nanoparticles were in suspension than as a dry powder. For frequencies between 100 Hz and 100 kHz, the average dielectric constant of ZnO NPs in DI water, in unrefined coconut oil, and as a dry particle are 368.63, 24.43, and 7.25, respectively.
Optical tweezers are important tools that are used in several scientific fields. An optical tweezers demonstration was developed by testing several different lasers, particles, and particle environments. The final product was a semienclosed 3D-printed casing with a sooted base plate. This demonstration picked up soot particles using a 250-mW 650-nm laser coupled to a 29-mm diopter focusing lens by Edmund Optics [1].
Naturally radioactive nuclides present in soils contain background radiation that humans are exposed to every day. Previous research suggests that there are high background radiation areas (HBRAs) caused by climate, geography, wind, and water currents that accumulate a higher concentration of these radionuclides. An investigation of the Nile Delta confirms the presence of minerals rich in U and Th from monazite and zircon, further suggesting that certain locations have a higher concentration of these radionuclides. The present work is a search for monazite in Great River Road State Park, near the Mississippi River. The acquired samples were measured with a low-background NaI(Tl) spectrometer and digital data acquisition system. Using γγ-coincidence spectroscopy to reduce background radiation, we were able to apply coincidence gates of known gamma-ray energies originating from 238U and 232Th decay chains to identify the presence of the radionuclides in the soil samples. From our results, we confirmed that there is an accumulation of minerals containing 238U and 232Th near the river. Our next steps will focus on calculating activities for quantitative results and collecting samples from an extended region along the river.
