Recent content by alba_ei

Where all these holographic visions come from? They appear to magically pop up and vanish out of nowhere.

From another related article "... it appears to draw in heat energy from its surroundings instead." There you have it. You cannot create energy out of nowhere.

No, or else you would get a perpetual machine of the first kind. A direct violation of the first law of thermodynamics.

Homework Statement The Attempt at a Solution %2.11 x=1:0.5:5; a=sqrt(2.8); n=[1:1:100]; Sn=prod(1-(x.^2)./(n.^2-a^2)); S_inf=(a/sqrt(a^2+x.^2)).*sin(pi*sqrt(a^2+x.^2))/sin(pi*a); e_n=100*(Sn-S_inf)./S_inf I know I can't use ./ if the two matrices are different, meaning x./n. How...

I've been doing some problems relative to car on an incline (and also boxes on an incline). Let's suppose we are given a problem with kinetic or static coefficient. I'm confusing when should or should not apply kinetic friction to a car, for example in some problems if brakes are applied then...

The cat would be in perpetual motion spinning around his back (the toast) forever, and will never hit the ground

Homework Statement \lim_{x \to - \infty} \frac{3^x-3^{-x}}{3^x+3^{-x}} Homework Equations \lim_{x \to - \infty} \frac{3^x-3^{-x}}{3^x+3^{-x}} = - 1 The Attempt at a Solution Im getting trouble when I try to evaluate this limit, altough the answer is -1 idont know how to get to...

In calculus, how good is to study from 2 or 3 Books at the same time? This is, for instance, study concepts and excercises based on the first (Stewart) and use the othes (Thomas and Edwards&Penney) for excercises. Is this a waste of time? Should I use only one?

Okay in this attempt of solution first i obtain the derivate of circle and ellipse. Circle: (x-2a)^2 + y^2 = r^2 Ellipse b^2 x^2 + a^2 y^2 = a^2 b^2 Derivate of circle y' = \frac{2a-x}{y} Derivate of ellipse y' = -\frac{b^2 x}{a^2 y} After i equal the derivate of...

The Same Integral... Two Different Answers! Homework Statement \int \frac{\tan x}{\cos^5 x} \,dx The Attempt at a Solution Solution 1 \int \frac{\tan x}{\cos^5 x} \,dx = \int \frac{\sin x}{\cos^6 x} u = \cos x \,\,\,\, du = -\sin x \,dx = -\int u^-^5 \,du =...

Homework Statement Consider a circle with centre (2a, 0) with radius such that cuts in right angle to the ellipse b^2 x^2 + a^2 y^2 = a^2 b^2. Find the radius Homework Equations (x-2a)^2 + y^2 = r^2 b^2 x^2 + a^2 y^2 = a^2 b^2 Answer: r^2 = \frac{3}{4} (3a^2 + b^2) The Attempt...

im looking for a book that shows the fundamentals of proofs cause I am starting and i want to start with the basics. thanks

Its \int \frac{{e^{3x} }{\sqrt {4 - e^{2x} } dx

Homework Statement \int \frac{e^{3x}}{\sqrt{4 - e^{2x}} \, dx The Attempt at a Solution Let u = e^x . Then du = e^x \, dx . So u^2 = e^{2x}. We have \int \frac{u^2}{\sqrt{4 - u^2)} \, du We make the substitution u = 2 \sin\theta . du = 2 \cos\theta \, d\theta . Then \int...

Well I like the maths and physics a lot so I am going to study an engineering, at this moment I am considering 3: aerospace engineering, civil engineering or mechanical engineering. I like the three, that's why i need your help to make a better choice. the diferences, etc.