Predicting How to Hit a Moving Target.
In a two dimensional ideal world without any external forces acting on an entity, if i were to have a turret that fires projectiles at a known velocity towards a moving target at a certain distance...
View ArticleMoon and tidal forces
Not homework here but merely curiosity. I was reading that on Titan there are rivers of methane, and that at least one is 400km long. Now I was thinking about the earth and moon; imagine that the moon...
View ArticleGauss's Law (Notational confusion)
I'm familiar with the differential form of Gauss's Law, which reads that ##\nabla\cdot\vec{E}=\frac{\rho}{\epsilon_0}##, where E is the electric field, ρ is the charge density, and ##\epsilon_0## is...
View ArticleE&M Faraday's Paradox
A conducting disk is rotating under a uniform magnetic field. Using Lorentz force F = qv x B, we can conclude that emf produced. Using Faraday's law, ∫E dl = 0 for any closed loops since there is no...
View Articlevirtual work of constraint forces
On a rigid body we usually use the formula δL=F*δP to calculate virtual work. My problem is about the force. This kind of force exists only before the contact. If I imagine a movement δP of the...
View ArticleProperties of adiabatic process
Hello Can we consider the sentence Adiabatic process cannot decrease entropy (found for example here) to be true in any circumstances ? Here I do not want to focus on any particular situation. Hence...
View ArticleThe Hummer
Every time I walk by the electrical transformer at the end of the lane, I hear a low humming noise(≈50Hz) that is continuous. I have observed this in all types of fans. I grab the hub so that it is not...
View ArticleMetal's effect on rf
What is the exact effect that metal has on rf (any electromagnetic waveform)? Is it attenuation, reflection, absorption or all of the these?
View ArticleMagnetic moment in a uniform/non- uniform magnetic field?
Hello, What's the difference? Being in a uniform or nonuniform magnetic field? If a magnetic moment(magnet) is place in both, what is the result?
View ArticleQuestion about photoelectric effect equation
If I write photoelectric effect equation to nhv = 1/2mv2 + W with n = 1, I am puzzled whether the n is larger than 1, such as 2 or 3, for which I will get the two- or three- photon absorption. Could...
View Articlepotential at a point
I recently wrote an exam and it had this question... There is an insulated copper wire carrying current.It is placed next to a conductor.What is the potential of this conductor? Is it more than that or...
View ArticleMagnetic Shielding of Detectors
My professor has given me a project, figure out how to magnetically shield some detectors which surround a solenoid. Now, we have mumetal tubs which fit the detectors, but he wants numbers. The...
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Interlacing pages of books - Need help with understanding
Hello all, I am working on a science project based upon paper, and I have chosen the affect of friction between two interlaced books. The attachment below is something I have found on the internet, as...
View ArticleWork done in moving a charge through an electric field
In electrostatics, when you apply an external force to a charge in an electric field to move it from A to B against the field, why is the force said to be equal to the force the electric field is...
View ArticleDoubts in electrostatics
I have a few questions pertaining to some concepts in electrostatics, I'd be grateful if someone would help me out. 1) When we place a positive point charge inside a hollow conducting sphere, at its...
View ArticleContextual Relationships Between Momentum, Energy, and Force.
I apologize in advance for the length of this post, if you wish to reduce reading skip to paragraph 5. Or if you are super lazy, the final paragraph. I've had long running difficulties with these...
View ArticleWhat is Time-Varying Voltage?
In circuits, we have no problem saying that the voltage difference between two point is [itex]\cos(\omega t)[/itex], but what does that actually mean? What is "voltage" in this case? I ask because my...
View ArticleHow does momentum, inertia and drag affect the motion of an object?
How does momentum and inertia affect changes in speed, when considering acceleration from thrust, or from decelleration from drag? Say, for a fixed mass of 100kg, at a velocity of 10m/s, is a force of...
View ArticleSphygmomonometers energy...storage?
So energy can only be converted... So when you squeeze the bulb on a blood pressure cuff, you are applying kinetic energy. Then the cuff fills with air and constricts the arm. Is the energy in the cuff...
View ArticleMage hand
Alright, so in Pathfinder (like Dungeons and Dragons) there's a spell that allows you to lift/move stuff within 25 ft with 5 pounds of force. A dagger weighs 1 pound [a rapier 2 pounds, a star dagger...
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