Recent content by Pandabasher

I think the point is that the thickness IS negligible as you say, so I've been trolled by Professor after all, haha. Thanks.

Homework Statement A soap bubble of radius 0.1mm has a wall thickness of 3.3x10^-8m, and is charged to a potential of 100V. Give a formula for the charge of the bubble. I know this is probably a really easy question, but I've only ever done problems with spheres of negligible wall...

Homework Statement The main sequence lifetime of a star, T, is related to it's luminosity, L, in an equation of the form T\proptoL^-0.7 Use this equation to derive the form of the mass-luminosity relation for main sequence stars. I know that I'm aiming for around L\proptoM^3.5 Don't...

Yeah I checked it with wolfram, its correct. Thanks for the tip, I'm not that good with integrals so I probably wouldn't have spotted that.

Using \displaystyle u= \frac {-1}{x} I get \displaystyle \int e^{u} u^{2} du Then I used integration by parts to get that equal to \displaystyle u^{2}e^{u} - \int 2u e^{u} du Then using integration by parts again I get that equal to \displaystyle 2u e^{u} - \int 2e^{u} which is...

Okay, thanks. I'll give it a go.

Homework Statement I'm in the middle of solving a D.E using integration factors, and I've ended up with an integral on the R.H.S which is as follows: \displaystyle \int \frac {e^ \frac {-1}{x}}{x^4} dx I've tried to use integration by parts to do it, but I keep having to use it again...

Homework Statement I'm an undergrad doing labs, and I was wondering how to get the error in a mean value, given that I know the errors of each individual value? This is probably a simple question, but any help is appreciated. Thanks, Matt.

Ah, thanks for clearing that up. My tutor used the binomial theorem, but didn't mention it, probably because he's been doing it for so long. Thanks for your help :)

Homework Statement Find constants a, b and c such that sin(∅)^5=asin∅+bsin3∅+csin5∅ Homework Equations The Attempt at a Solution I expressed sin in its complex form (if that's what its called) and put it to the power 5, and then multiplied each bracket out one at a time, and...