# All Questions

63 views

### Is it possible to determine maximum frequency of a disc using a relative circumference?

On Wikipedia there is an article that shows how to calculate the relativistic effects on a rigid spinning disc, I am referencing the formula under the "Ehrenfest's argument" section in the link. The ...
26 views

### Effectiveness of phase-change materials vs water for heat storage?

I'm trying to understand the benefit of specialized phase-change materials vs. water for absorbing heat in a home during the day. It's my understanding that selecting phase-change materials whose ...
42 views

### Can velocity be negative? [on hold]

In free fall I use the formula V=g*t and g is negative(-9.8m/s^2). It gives me negative.
41 views

### Why do electrically conductive materials tend to be thermally conductive?

It's hard finding substances that are good insulators of one and conductive of the other. Why the correlation? And why do some materials not have this correlation?
19 views

### Calculate Pendulum force [on hold]

I would like to calculate the impact force of a free fall 16kg Pendulum ball hitting the wall at 1.5m away. Please help. Thanks
64 views

### Do any two points in Minkowski spacetime determine a unique line?

Any two points in a Euclidean space determine a unique line, but I wasn't sure if this result generalized to Minkowski spacetime given that the latter is not a Euclidean 4-space, but is, instead, a ...
54 views

### Collision between a “spring” and a particle

I am currently attempting to create a simple 2D physics engine, and I just need to know how to solve a certain collision. I have particles, and between any two particles, springs can be connected. ...
67 views

20 views

### External and internal resistance to airflow

If an aircraft was travelling at 100mph an hole was opened to allow 100mph into the cabin,then the airflow is feed into an amplifier like a ramjet and the airflow out of the ramjet was increased to ...
22 views

### Should static electricity affect a Crookes radiometer?

I've been playing around with a Crookes radiometer for fun and I happened across something I can't figure out. I know the fundamentals of the radiometer (e.g. partial vacuum, thermodynamics, etc.), ...
34 views

### Particle Under Constant Acceleration Problem [on hold]

A car travelling at a constant speed of $45.0\:\mathrm{m/s}$ passes a trooper on a motorcycle hidden behind a billboard. One second after the speeding car passes the billboard, the trooper sets out ...
41 views

20 views

### A bar magnet is brought close to, but does not touch, a paper clip [on hold]

The paper clip moves toward the magnet. What does this observation show about the field associated with the bar magnet?
19 views

### Derivation of effective mass equation in carbon nanotubes

I am trying to reproduce the calculations in the paper here by Ando and Nakanishi and am already stuck on equation 1. It is stated that in the vicinity of $\epsilon=0$ the amplitude of the ...
70 views

### Newton's Cradle: why does it stay symmetric? [duplicate]

How is it that always the same number of balls leave at the other end in Newton's cradle. I understand that the momentum needs to be conserved, but as momentum is defined as p=m*v couldn't you have a ...
20 views

### PARALLEL COMBINATION OF SUPERCONDUCTORS AND RESISTORS [duplicate]

........................please reply to the question above in the picture. I have tried a lot and have thought about it for a long time. Please help me and answer in simple words. AND I REQUEST NOT ...
34 views

### Could be calculated radius of proton from its mass [on hold]

$r_p m_p = 2 h / π c$ , $r_p = 8,4123 E-16$ m or $r_p = 2L_p^2 c^2 / G m_p = 8,4123 E-16$ m close enough to experimentally determined radius: $99,96\%$ references :DOI: 10.1126/science.1230016 ...
21 views

### Particles A and B have different masses and net electric charges [on hold]

is the size of the electric force on particle A due to particle B the same as that on B due to A??
35 views

### Why do LIGO use a quarter wavelength for detecting gravitational waves?

I have already researched into this and I am left slightly confused still. I have gathered that the use of a quarter wavelength is to turn a linearly polarised wave into a circularly polarised wave. ...
34 views

### High surface area for given volume [on hold]

What can be a example similar to mathematical Koch flake that could be found in nature... where for a given enclosed volume its surface area is indefinitely large?
53 views

### Measuring tides in a swimming pool

The tidal range of a perfectly fluid inertialess ocean on the Earth (taking into account lunar tides only) is approximately half a metre: this is the range between "high" and "low" points of an ...
54 views

### Does spontaneous emission count as a measurement?

It is my understanding that in the density matrix formalism for open quantum systems the environment-induced measurements/collapses/projections are accounted for by the Lindblad superoperator (from ...
56 views

### Are these capacitors parallel or in series?

I am a bit confused. The authors say these conductors are parallel when the switch is on. But to me it looks like they are in series since the handle is insulating. How can you explain that they are ...
32 views

### What exactly is meant by Moment of inertia of a body? [on hold]

Physical significance of Moment of inertia, not just the formula. any help
40 views

### Physical Significance of Wigner Equation, Wigner Current

I am Currently doing a reading about Wigner function in Quantum optics, I learnt that the Wigner function maps the Quantum mechanical operators to phase space functions in phase space, so we can talk ...