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Articles 1 - 8 of 8
Full-Text Articles in Physics
Toy Blocks And Rotational Physics, Gabriele U. Varieschi, Isabel R. Jully
Toy Blocks And Rotational Physics, Gabriele U. Varieschi, Isabel R. Jully
Gabriele Varieschi
Have you ever observed a child playing with toy blocks? A favorite game is to build towers and then make them topple like falling trees. To the eye of a trained physicist this should immediately look like an example of the physics of “falling chimneys,” when tall structures bend and break in mid-air while falling to the ground. The game played with toy blocks can actually reproduce well what is usually seen in photographs of falling towers, such as the one that appeared on the cover of the September 1976 issue of The Physics Teacher.1 In this paper we describe …
Kerr Metric, Geodesic Motion, And Flyby Anomaly In Fourth-Order Conformal Gravity, Gabriele U. Varieschi
Kerr Metric, Geodesic Motion, And Flyby Anomaly In Fourth-Order Conformal Gravity, Gabriele U. Varieschi
Gabriele Varieschi
In this paper we analyze the Kerr geometry in the context of Conformal Gravity, an alternative theory of gravitation, which is a direct extension of General Relativity (GR). Following previous studies in the literature, we introduce an explicit expression of the Kerr metric in Conformal Gravity, which naturally reduces to the standard GR Kerr geometry in the absence of Conformal Gravity effects. As in the standard case, we show that the Hamilton–Jacobi equation governing geodesic motion in a space-time based on this geometry is indeed separable and that a fourth constant of motion—similar to Carter’s constant—can also be introduced in …
Intonation And Compensation Of Fretted String Instruments, Gabriele U. Varieschi, Christina M. Gower
Intonation And Compensation Of Fretted String Instruments, Gabriele U. Varieschi, Christina M. Gower
Gabriele Varieschi
We discuss theoretical and physical models that are useful for analyzing the intonation of musical instruments such as guitars and mandolins and can be used to improve the tuning on these instruments. The placement of frets on the fingerboard is designed according to mathematical rules and the assumption of an ideal string. The analysis becomes more complicated when we include the effects of deformation of the string and inharmonicity due to other string characteristics. As a consequence, perfect intonation of all the notes on the instrument cannot be achieved, but complex compensation procedures can be introduced to minimize the problem. …
Simulating A Guitar With A Conventional Sonometer, Zily Burstein, Christina M. Gower, Gabriele U. Varieschi
Simulating A Guitar With A Conventional Sonometer, Zily Burstein, Christina M. Gower, Gabriele U. Varieschi
Gabriele Varieschi
In this paper we present a simple way to convert a conventional sonometer into a simulated fretted instrument, such as a guitar or similar, by adding a fingerboard to the sonometer. In particular, we use this modified apparatus in relation to the problem of the instrument intonation, i.e., how to obtain correctly tuned notes on these string instruments. The experimental procedures presented in this study can become a more structured laboratory activity to be used in general physics courses or acoustics classes.
Astrophysical Tests Of Kinematical Conformal Cosmology In Fourth-Order Conformal Weyl Gravity, Gabriele U. Varieschi
Astrophysical Tests Of Kinematical Conformal Cosmology In Fourth-Order Conformal Weyl Gravity, Gabriele U. Varieschi
Gabriele Varieschi
In this work we analyze kinematical conformal cosmology (KCC), an alternative cosmological model based on conformal Weyl gravity (CG), and test it against current type Ia supernova (SNIa) luminosity data and other astrophysical observations. Expanding upon previous work on the subject, we revise the analysis of SNIa data, confirming that KCC can explain the evidence for an accelerating expansion of the Universe without using dark energy or other exotic components. We obtain an independent evaluation of the Hubble constant, H0 = 67:53 kms-1 Mpc-1, very close to the current best estimates. The main KCC and CG parameters are re-evaluated and …
Toy Models For The Falling Chimney, Gabriele U. Varieschi, Kaoru Kamiya
Toy Models For The Falling Chimney, Gabriele U. Varieschi, Kaoru Kamiya
Gabriele Varieschi
In this paper we review the theory of the ‘‘falling chimney,’’ which deals with the breaking in mid-air of tall structures when they fall to the ground. We show that these ruptures can be caused by either shear forces typically developing near the base, or by the bending of the structure which is caused primarily by the internal bending moment. In the latter case the breaking is more likely to occur between one-third and one-half of the height of the chimney. Small scale toy models are used to reproduce the dynamics of the falling chimney. By examining photos taken during …
Wormhole Geometries In Fourth-Order Conformal Weyl Gravity, Gabriele U. Varieschi, Kellie L. Ault
Wormhole Geometries In Fourth-Order Conformal Weyl Gravity, Gabriele U. Varieschi, Kellie L. Ault
Gabriele Varieschi
We present an analysis of the classic wormhole geometries based on conformal Weyl gravity, rather than standard general relativity. The main characteristics of the resulting traversable wormholes remain the same as in the seminal study by Morris and Thorne, namely, that effective super-luminal motion is a viable consequence of the metric. Improving on previous work on the subject, we show that for particular choices of the shape and redshift functions the wormhole metric in the context of conformal gravity does not violate the main energy conditions at or near the wormhole throat. Some exotic matter might still be needed at …
Conformal Gravity And The Alcubierre Warp Drive Metric, Gabriele U. Varieschi, Zily Burstein
Conformal Gravity And The Alcubierre Warp Drive Metric, Gabriele U. Varieschi, Zily Burstein
Gabriele Varieschi
We present an analysis of the classic Alcubierre metric based on conformal gravity, rather than standard general relativity. The main characteristics of the resulting warp drive remain the same as in the original study by Alcubierre, that is, effective superluminal motion is a viable outcome of the metric. We show that for particular choices of the shaping function, the Alcubierre metric in the context of conformal gravity does not violate the weak energy condition, as was the case of the original solution. In particular, the resulting warp drive does not require the use of exotic matter. Therefore, if conformal gravity …