One more thing. Would I be right to assume that using the 20log equations give the ratio k of power density loss that corresponds to the electric field loss? I ask this because the teacher uses his ratio k that he found with the 20log equations, then argues that since P1/P0 = E1^2/E0^2, the...
Homework Statement
Let E1 be the electric field 1cm into a person's skin and E0 be the electric field on the surface of that person's skin. If the field loses -486db/m and E0 = 64.1, find the value of E1.
Homework Equations
E1/E0 = k, with k < 1
The Attempt at a Solution
Well...
Friction as B times angular speed??!
Hi,
My control systems book uses a weird notation for the moment caused by friction in a rotating motor. The equation is
Tfriction = B×dθ/dt
Where does this equation come from? The author assumes the reader is already familiar with this equation...
Thanks for the reply guys! I figured out how to solve it by deriving on both sides, putting the v's and dv on one side and the dt on the other side then integrating again.
I still have a question. What made the first equation non-linear? I'm not sure why Laplace cannot be used here.
Thanks!
I stumbled upon this diff. equation, which is a function of speed (v). Is there a technique I can use to solve it?
av(t) = b - c∫v(t)^2dt - d∫v(t)
Can I simply differentiate on both sides to get rid of the integral of the squared function, then use Laplace? The integrals go from 0 to an...
Hi,
Laplace transforms are a fundamental tool in electrical engineering and control systems engineering. Unfortunately my University is having us read books that use Laplace Transforms, but I've never learned the theory rigorously! For example the book I'm currently reading state briefly that...
I understand linearisation is mostly used in engineering, since real-life systems must use these approximations. I'm going to assume this is why physicists aren't really comfortable answering my question. Does anyone know a forum that could be better suited for this engineering question...
Hey guys.
We were given a problem, which was to consider bv^2 as the force acting upwards on a body falling in water. We were asked to find the depth at which a body entering the water at 5 * ve (terminal speed) would end up with a speed of 1.1 * ve.
Starting from -bv^2 + mg = ma, the first...
Thanks. I think I see it now. Half of the "rope" (spring) length increase must be "used" to increase the length of the rope on the other side of the pulley. This other half of the length increase is not used to displace the system towards the bottom.
It follows that the load would indeed only...
I know in a double pulley system, the rope moves twice the distance of the load. What about a system such as this? Would the stretch distance of the spring be twice the moved distance of the load?
I'm having trouble visualizing these things.
Thanks!
Also by writing this I realized I have the equation -2 = 0.173wba for the y direction since obviously point B has no vertical speed. I checked at the end of my book and that was the right answer. However, I would like to know why I cannot solve this problem by replacing the linear speed vectors...
Guys I tried all your suggestions but I still cannot solve this... My exam is coming up soon and I am starting to get stressed out. The direction of Va is obviously -2j, Vb is -xi (unknown value) and Va/b is to the bottom and right, so something i + something j.
Homework Statement
Homework Equations
I'm dumbfounded by this problem. I can solve the (I think) harder problems with two fixed points and three rod segments. All the examples given in this book are of such "harder" problems and I have absolutely no example that resembles this...
General "How stuff works" video capsules, blog or podcast?
Hey, I'd really like to spend a few minutes (15-30 minutes per day) learning about how random stuff works. Anything from electronics to cars to specific pieces of technologies, to industrial processes, etc.
I'm posting in this...
Ya sorry I messed up the HP/W conversion, I was tired haha. Yes, an ideal converter would have the same line-neutral voltage on all it's legs, but that is not the case with rotary phase converters. Even digital converters have a high leg.
Google "Phase converter wild leg".
I know the 240V...