Tsiolkovsky rocket equation
Hello, I am trying to understand the Tsiolkovsky rocket equation. I am looking at this right now: http://www.math24.net/rocket-motion.html they said that the momentum of the rocket itself is: p1 =...
View ArticleMagnetic Plasma Manipulation
I am attempting to devise an experiment to test exactly how successfully plasma can be manipulated by a natural magnet. Ideally, the gas to be ionized would be isolated in a vacuum tube, where it would...
View Articlewhy does a potential go to zero with infinite distance?
in physics II, i learned about how the electric potential goes to zero as r goes to infinity. Okay, well, this was when we were dealing with two positive charges. ie a repulsive force. now i'm learning...
View Articlewhy is this wrong? (gravitational flux)
in my notes i have.. [itex]\Phi[/itex] = [itex]\int[/itex] [itex]\vec{g}\cdot[/itex]dA = g(4[itex]\pi[/itex]r2) = -[itex]\frac{GM}{r^2}[/itex](4[itex]\pi[/itex]r2) which yields...
View ArticleRoughly, how many kg of fuel do we need to get x lbs into space?
Is there a ballpark or rough formula to get x lbs into space how much kg of fuel is needed to do so? I know that the more fuel you have the more fuel you also need just to carry the extra fuel!
View ArticleCoefficient of Drag based on Cd for 2d plate
I have made a theory to calculate a coefficient of drag based on Cd for a 2d plate. I will refer to the coefficient of drag for a 2d plate as just D. Lets say that we had a 2d plate and it was tilted...
View ArticleBest type of wire for magnetic field?
I'm looking at getting a lengthy piece of wire, looping it around into either a circle or an ellipse and running a current through it to get a magnetic field, however I'm unsure what type of wire to go...
View ArticleRegrettable definition/notation
hello, I would like to hear some comments about this situation. There seems to be two incompatible definitions concerning "Tensor Product" and "Dyadic product" of two vectors. The mathematical...
View ArticleElectric Field above a Quarter Disk
1. Problem Statement. Find the Electrostatic Field at a distance z above the xy-plane and along the z-axis due to a constant surface charge σ confined to the region a < √(x2+y2) < b, 0 < α...
View ArticlePotential energy and work
Hello everyone! When we do work against a field on an object, why must the force we apply on it be equal and opposite to that of the field? If the object is initially at rest, then shouldn't we be...
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Reaction-at-a-distance: Might charged plates immediately repel?
Imagine that we have a pair of parallel plates, [itex]A[/itex] and [itex]B[/itex], separated by some distance as in Fig. [itex]1[/itex] below. At time [itex]t_1[/itex] we simultaneously charge both the...
View Articlefind the perifocal
In Kepler: Given: x0, y0, z0, vx0, vy0 and vz0 I can find Longitude of the Ascending Node(N), inclination(i), Argument of Periapsis(w) and True Anomaly(TA). I can find the perifocal(the plane of the...
View Articlewhy magnets H field oposes its B
hi is there a basic way to picture how the H field inside a permanent magnet opposes its B field (i know the eq's are made to say it does just how to visulize this) -ie H seems to be the magnets atomic...
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Magnetic field due to current in straight wire(Biot-Savarts)
Hello. The Magnetic Field lines are concentric circles for a Straight wire.Hence the points above and below point B should not contribute to the magnetic field at A. So Why do we integrate the...
View ArticleArchimedes principle and shapes of the body
Archimedes principle of the force of upthrust = weight of water displaced by the body immersed , but is this law independent of the shape of this body. If we use the idea that the upthrust = P*A on the...
View ArticleVariable Resistors in a Voltage Divider
My textbook says that in a voltage divider (voltage source Vin, then a resistor, then another path that leads to Vout, Resistor two, Ground, that it is a bad idea to use variable resistors for BOTH of...
View ArticleQuestion about the units of acceleration?
The general unit if acceleration is meter per second per second. Let's play with the unit of the standard acceleration due to gravity which is 9.8 meter per second per second. Thus how acceleration can...
View ArticleHow much induced voltage on sphere?
Hi, Assume that one has a pair of metal spheres, A and B, some distance apart. A is connected to, say, a small van der Graaf generator and B is connected to a voltmeter which is then connected to...
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Calculating the critical load for a system
Dear all, I am stuck with a problem where I must show that the lowest critical load converges to a certain value if the number of elements increases(see figure) I can assume a certain set of numerical...
View Articlekinematics question
a boat takes 3.1 hours to travel 15 km down a river, then takes 5.1 hours to travel the same distance upstream. how fast is the river traveling. I found the boat is traveling at 4.84km/hr down the...
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