Recent content by Lagraaaange

Talk about making assumptions and false claims as a "scientist". I actually have quite a high self image . I apologize for posing questions to others in hopes of getting everyone's opinion in order to make a good decision. I'm definitely going to reconsider my life because of your post and I'll...

Do you guys think exams and problems in physics really reflect your knowledge of the subject? I find myself having superior knowledge of theory in my courses relative to classmates (I often explain it to them), but then I can't reproduce this on exams which are all computation. What do you think?

But I've got both case down, right? The former being for two isotopes into two and the latter for one to another?

So how would one prepare for an exam question like this?

Thanks. Let's hope my professor agrees.

Suppose at time t a sample N1 goes to N2 with rate λN1. Then N1(t) = Kexp(-λt). Let us choose t=0 to be when no particles decayed. Let N0 be total amount of particles, (N1+N2), thus N1(0) = N0 => N1(t) = N0exp(-λt). Note N0-N1(t) = N2(t) = N0(1-exp(-λt)) So N1(t)/N2(t) =...

How does one obtain the conversion result, say where one isotope is converted to another?

Consider the last line in my outline. It would be -λ+λ = 0. This would result in a nonsensical answer. Also this tells me that λ2 must be greater than λ1 unless the ratios result in less than 1 in which case the log would be negative and I'd be ok. I have an exam on a question of this type so...

If the rate is for one isotope to another, wouldn't the lambdas just cancel out? I mean would giving 1 lambda even make sense given two rates at two times?

This is mainly to make sure none of my homeworks were misplaced.Also to include a "Thank you for the semester"

Is it ok to email a professor asking them to confirm your grades to this point e.g. you send them all your homework grades and midterm grade in case of error and ask them about your final exam score? Would this be nagging and or condescending. Wouldn't want to hurt my image just before final...

My professor said one can use E=mc^2

How would one get the energy production in a star if only given the mass of the star? Something involving mc^2 I suppose?

I don't see it. If I change it to a conversion of one to the other wouldn't I have a differential equation of the form: d(N2-N1) = -λdt

1. Is this "right" in terms of variables; that is, are the mathematics and physics ok? 2. In the case of one isotope being converted to the other I would have one λ? I would still need the constant to be provide, right? I mean I'd need a half life or something if I don't have λ given.