John Rennie
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 Oct 29 comment Proton Quantum Tunnelling in Hydrogen Bonds: Influence on Properties of Deuterated Ice? I've always understood hydrogen bonding to be a dipolar interaction. It isn't clear to me why tunnelling would be involved. Oct 29 comment Current carrying wire to suspend in midair? Hi and welcome to the Physics SE! Please note that this is not a homework help site. Please see this Meta post on asking homework questions and this Meta post for "check my work" problems. Oct 29 revised Current carrying wire to suspend in midair? edited tags Oct 29 revised What is the distance covered? edited tags Oct 29 comment What is the distance covered? Please note that this is not a homework help site. Please see this Meta post on asking homework questions and this Meta post for "check my work" problems. Oct 29 revised Find initial temperature of ideal gas when heated by 400K and volume doubles edited tags Oct 29 comment Find initial temperature of ideal gas when heated by 400K and volume doubles Hi and welcome to the Physics SE! Please note that this is not a homework help site. Please see this Meta post on asking homework questions and this Meta post for "check my work" problems. Oct 29 comment Connecting two antennas to provide signal I would guess you're hoping that the external aerial will convert the radio wave to an electrical signal, and the internal aerial will convert the electrical signal back into a radio wave. So the end result is that the radio wave is piped into your room. Is this correct? Oct 29 comment 2s orbital wavefunction has non-zero probability at $r=0$? @Will: I assume the question was What is the probability of finding an electron in the 2s orbital inside the nucleus? otherwise it's a meaningless question. If so the answer is $\int_0^R P(r)dr = \int_0^R \psi^*(r) \psi(r) 4\pi r^2 dr$, where $R$ is the radius of the nucleus and $P(r)$ is the RDF. For the $2s$ orbital this will be non-zero. Oct 29 comment What evidence is there that infinities exist anywhere around or within a black hole? @MaxWilliams: in GR the singularity is not part of the universe. GR describes the universe as a mathematical structure called a manifold, and the singularity is excluded from the manifold. GR does not predict what happens at the singularity, only what happens when you get infinitessimally close to it. Oct 29 answered What is the dilation relation of the distance to a moving point (in special relativity)? Oct 29 reviewed No Action Needed What is the importance of the biquadratic interaction in the AKLT model? Oct 29 reviewed Close What is the dilation relation of the distance to a moving point (in special relativity)? Oct 29 revised Explaning Motion of a Man and Spacecraft Orbiting the Earth edited tags Oct 29 comment Is the curvature formed due to mass/volume of spactime convex or concave? It is neither. The terms convex and concave refer to the Gaussian curvature of a 2D Riemannian manifold. Spacetime is a 4D pseudo-Riemannian manifold and asking whether the curvature is convex or concave is meaningless. Oct 29 comment Significance of Time constants in LR and RC circuits I'm voting to close this question as off-topic because it shows insufficient prior research Oct 29 comment Significance of Time constants in LR and RC circuits Can you give us an idea of what research you've already done. For example have you read the Wikipedia article on the RC time constant. Oct 29 answered Liquid electromagnet Oct 29 reviewed Leave Closed Gravitational Force Oct 29 reviewed Close How can I find static friction without knowing the mass of the object?