# Search results

1. ### Rotational Dynamics

Thanks, in the absence of an answer I've reread my notes, and managed to solve the problem. I've had to put everything in it's place in my head(all the different accelerations, and velocities). English is obviously not my mother language so I probably got the terminology part wrong.
2. ### Rotational Dynamics

Homework Statement A wheel is spinning at n=1200rpm. The wheel starts to linearly decelerate, and after t=100s it stops. Determine the velocity, and acceleration of a point 10cm from the center of the mass, after 50 seconds of decelerating. The radius of the wheel is 30cm. Homework Equations...
3. ### Torque and vectors

I've tried taking the perpendicular component, but not sure what the lever arm is. I'm not sure how to determine the line of action.
4. ### Torque and vectors

Homework Statement So I was wondering how do we account for vectors that are at a certain angle. The problem that I'm having with the picture is: if I was calculating torque from point B, how would I account for the vector G. Homework Equations The Attempt at a Solution I've...
5. ### Conservation of energy - spring

Should it be g*m*(h+∆L)=(1/2)*k*(∆L)^2, because if it's on both sides it's the same
6. ### Conservation of energy - spring

Homework Statement Hello, I'm having a problem with this. So we drop the weight on this spring, and the question is: how much does the spring compress? The mass is 5kg, the height 0,4m, and the spring elasticity factor k=1700N/m. Homework Equations The Attempt at a Solution I've...
7. ### Multivariable domain

Maybe should have put the part that was troubling me in the question. So basically, where is z>=-sqrt(x^2+y^2) supposed to be?
8. ### Multivariable domain

Homework Statement I'm having a problem with solving the domain of |x^2+y^2|<=|z^2|. Homework Equations The Attempt at a Solution From what I got this should be separated into two expressions: x^2+y^2<=z^2, and x^2+y^2>=-z^2. The later doesn't have a real solution because of the...
9. ### Series convergence problem

No it's -n alright, but I've been switching them up along the way. Now I see my problem. Thanks
10. ### Series convergence problem

Homework Statement So I need to determine if the series \Sigmaln(1+e^{-n})/n converges. Homework Equations The Attempt at a Solution I know it does, but cannot prove it. Wolfram says that the ratio test indicates that the series converges, but when I try to solve the limit I get that it...
11. ### Falling functions

That makes sense, but I probably should have said that I was wondering if it converges conditionally. Thanks for clearing things up!
12. ### Falling functions

My textbook doesn't say it needs to be the absolute value, although it's under the absolute convergence chapter. When I think of it, it makes a lot of sense that it needs to be absolute convergence. But then again if we pair lim(n->inf)a_n=0 with a decreasing function I think we get the same thing.
13. ### Falling functions

Yes, that is what I meant. English is my second language so math terminology in English is not my strong point. That was my question, and thanks for clearing it up!
14. ### Falling functions

Homework Statement Hello, I was wondering if a falling function needs to fall on it's whole domain? I was solving a series with alternating sings. It says that if the series has alternating signs, that it converges if: 1) lim(n->0)an=0 2) an is a falling function I was solving this...
15. ### Integral solving problem

Thank you very much for your help!
16. ### Integral solving problem

Homework Statement I've been trying to integrate the following: ∫\frac{cos^3(x)}{\sqrt{sin(x)}}dx Homework Equations The Attempt at a Solution First, I substituted sin(x) with t, and got dt=cos(x)dx => dx=\frac{dt}{cos(x)}. After that I got ∫\frac{cos^2(x)}{\sqrt{t}}dt Then i transformed...
17. ### Finite limit problem

I understand now! Thank you very much for your help!
18. ### Finite limit problem

From all this my guess will be 1, but still not clear why. Is it because lim x->0 means that x !=0 but rather close to 0? Meaning some infinitesimal number ^0=1? Am i getting that correctly?
19. ### Finite limit problem

It was a typo. Fixed, and yes that is the limit i was referring to!
20. ### Finite limit problem

Homework Statement I've read in my textbook, and confirmed via WolframAlpha that lim x->0 (cosx/x^0) =1 , and need an explanation for it. I thought it should be ∞ or something undefined, since 0^0 is undefined. Homework Equations The Attempt at a Solution I tried to use L'Hospitale on the...
21. ### Function domain help

Thank you very much eumyang and LCKurtz! This really helps a lot. Now i realize that i have to look at it as a whole, and not two separate inequations. I don't know if there's some repping system on this forum but you definitively get my thanks/+1
22. ### Function domain help

I did take that in account, and made 2 scenarios (unlike the example): 1.positive or zero/positive 2.negative or zero/negative In the first case i get <-inf,-2]U[3,+inf> and <7,+inf> !! In the second case i get [-2,3] !! and <-inf,9> So how do i get half the right answer in 2...
23. ### Function domain help

Could you explain why? I understand the lower part, but the quadratic inequation bothers me. The first index is a>0 => parabola with a minimum vertex, meaning it's values are >=0 from <-inf,-2]U[3,+inf>. That is the reason i made this thread.
24. ### Function domain help

Homework Statement Hello! Could someone explain some things presented in this example: http://i.imgur.com/wVOxf.png My friend, and I haven't been able to crack it. I get all the x-conditions right, but can't put the whole thing together into a domain. Here it's presented that xe[-2,3] due to...