Recent content by Andrew Mason

Just so I am clear on the linkage, the angle of BD to the extension of BC is a fixed 120° and B is free to slide along BC. You are being asked then to find the linear velocity of D and angular velocity of BD when the angle of AB to the extension of AC is 60°. The angular velocity of AB is a...

.... Wade is a journalist and has developed his own 'theories' about race and genetics. He has come under a lot of criticism for his most recent book (2014), A Troublesome Inheritance: Genes, Race, and Human History. Here is a rather uncharitable review of that book and Wade's approach...

This graphic from the paper published in Nature in 2015 may help explain the data that Reich was using: The green bars represent the proportion of genes in the populations in the stated country or region added from migrants from the steppe regions of eastern Europe and Asia (Yamnaya); The...

So 3 times the fundamental is a harmonic (a twelfth) but not 1.5 (fifth). You might find musicians who would disagree that a perfect fifth is not a harmonic interval. AM

The OP was using "overtones" to refer to the sequential harmonics above the fundamental tone. I was just doing the same. I don't think there is a hard an fast rule relating musical terms (overtones) and physics terms (harmonics). AM

It depends on whether these statements can be true: 1. "most Europeans are descended from the first settlers who arrived during the Upper Paleolithic Era. " and 2. "Only a minority arrived during the Neolithic age." by Wade and 3. "... just five thousand years ago, the people who are now the...

As someone with a long held interest in, but no academic background in, molecular biology, I find this is helpful. I became interested in the idea of using polymerase inhibitors to prevent the SARS-CoV-2 virus from replicating and started this thread in June of 2020 on Remdesivir as well as a...

There is a difference, not necessarily a total contradiction. Based on genetic analysis of European skeletons older than 5000 years, inhabitants of Europe before about 3000 BC had mixed genes from hunter-gatherers and Anatolian farmers. Both authors agree on that. Hunter-gatherers arrived in...

It was in 1933, long after Haber's 1918 Nobel prize for making nitrogen fertilizer. The reason, however, is not entirely clear. Rutherford maintained a life-long friendship with Otto Hahn, with whom he worked closely in his Montreal lab. Hahn had worked with Fritz Haber in Germany during WWI...

Yes. But it is not flying level at the bottom portion of the flight path, which is a quarter circle with radius 300m. AM

The question is a bit of a trick question. It says the maximum upward acceleration is 6g. The correct answer is given by ##\vec{a}=-\frac{v^2}{r}\hat{r}=-6\vec{g} ## where the positive direction of ##\vec{a}## is up and that of ##\vec{g}## is down. This results in ##v=132.8 m/s## (assuming...

Interesting point. The only opening for sound is the mouth of the pipe and for sound energy to exit there is an acoustic coupling between the standing wave in the pipe and the travelling wave in the external air. As you point out there is a difference between the ambient air pressure outside and...

Yes, but the stopped wooden organ pipe does not produce a square wave. I am not suggesting that the physics of musical instruments is simple. But according to all the literature I have found, the fundamental and harmonics of an organ pipe are determined by the length of the pipe and whether...

Right. That is how the vibrations originate. So I am confused by your previous reference to "Even harmonics are generated by asymmetrical clipping of the pressure amplitude, like a rectified sinewave. Odd harmonics are generated by symmetrical clipping about zero, like a sinewave with flat...

?? In an organ pipe, the harmonics do not result from clipping sound wave amplitudes. The fundamental and harmonics are generated by resonance within the pipe, which allows standing waves only in discrete multiples of half wave-lengths (open pipe) or discrete odd multiples of quarter...