Radius of ball matters in fall speed!
In physics class today, our teacher wanted to demonstrate that mass doesn't have an effect on fall speed. (The class was about gravitational potential energy becoming kinetic, mgh = 1/2 *mv^2 and all...
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Will this centrifugal fan design work?
Hello everyone. I am working on a VTOL RC craft that I hope will work. I was planning on using a centrifugal fan to accelerate air radially (instead of a squirrel-cage design), and putting 45 degree...
View ArticleWeightless Vacuum Container maximum height
Assume you have a weightless constant volume container "filled with" vacuum. If you let it float in the atmosphere, how "high" would it go? I guess at some point Archimedes' principle should fail. What...
View ArticleBoltzmann Entropy for micro state or macro state?
From theory, we know that Boltzmann entropy for a given distribution, defined through a set of occupancy numbers {ni}, of the macrostate M, is given by: S=k log(Ī©{ni}) where omega is the number of...
View ArticleNewtons Cradle 2 balls
We have a Newtons cradle , when you let go of one ball at one end you know what happens. Rlease one ball and the other side has a ball osciallte. But if you release two balls (with a 5 ball cradle) ,...
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Propane Combustion (btu/ft^3) how fast it'll move a piston
I hope I can make this understandable. I'm working on a design to utilize combustion of propane to cycle a piston. I'll attach a gif to make it more simple to understand. When the cylinder is filled...
View Articlewhy p type semiconductor is electrically neutral
why p type semiconductor is electrically neutral and what is the concept of drift current?
View ArticleExpressing sol. of Poisson eqn. in terms of vol. and sur. integrals.
Hi, Referring to Jackson's Electrodynamics 3ed, page 197, line 5. He assumes that the magnetization can be divided into volume part and surface part, thus generating eqn 5.100. This is fine. In a...
View ArticleA question about geosynchronous orbit
I a question regarding an object, that is originally in geosynchronous orbit, but then thrusted straight down. Will the object land directly on where it was hovering over while in the geosynchronous...
View Articlenewton's third law in terms of inertial position vectors for n-body system
Assuming $$\vec{r_{a}}$$ and $$\vec{r_{b}}$$ is calculated from an inertial frame of reference. then for any two objects (named a and b) in a system of more than two objects, Is this the newton's third...
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Time period of an oscillating body...
In the above figure, what would be the time period of the body(in red) under gravity, neglecting any non-conservative forces? And what do call this type of situation? A gravity well or sth?
View ArticleHow do electricity and superconductors work?
Electricity has been a mysterious entity plaguing my mind since last year when I learnt about it in class. I am unable to understand why electrons move the way they do when a circuit is formed, nor...
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The fuel level inside a tank.
. I do not know how to solve this problem. I need some help. How would we find out A, the angle between the horizontal and the fuel level line inside the tank of a car?. The car speed does not change,...
View ArticleIm curious about magnets... Can they be a source of energy or not?
Greetings fellow members!(New guy!) Before I would start, I've already read a lot of the threads related to "magnets" and "energy". I do undertand the PF forums rules. So please don't lock this thread...
View ArticleDesign a condenser of a steam power plant
This question is from my textbook: Thermodynamics an Engineering Approach 7ed SI Units, cengel. It is problem 10-129 and I can't seem to figure it out. Design the condenser of a steam power plant that...
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Can't understand procession
I'm curious about how precession works. From what I thought I understood about angular momentum and torque vectors, the direction that they point are by arbitrary convention using the right hand rule....
View ArticleHow friction depends on surface area...
I'd read that friction is independent of the surface area of the bodies in contact. But somewhere in the internet I found that this explanation was just a good approximation and that friction actually...
View ArticleHow liquid pressure = dgh can be generalized
I've seen the standard derivation of the expression for liquid pressure P = dgh where, d = density of the liquid; g = acceleration due to gravity; h = height of liquid column in many text books has...
View ArticleAngular momentum conservation in helicopters...
I had read in a book that the primary reason for the use of tail rotor in a helicopter is to counteract the rotation of the main body generated as a response to the rotation of the main rotor blades to...
View ArticleAdvanced Lienard-Wiechert potentials and fields?
The standard (retarded) LiƩnard-Wiechert potentials and the expressions for the electric and magnetic fields derived from them are all evaluated at retarded time [itex]t_r = t - R(t_r)/c[/itex]:...
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