Recent content by Alexstre

Homework Statement A cylinder of radius a with a hole through it (of radius a/2) is filled with a material of resistivity p_2. Show that the total resistivity is now 4*(pL / pi*a²) (p_2 / 3p_2 + p) Homework Equations R=pL/A The Attempt at a Solution I started with a full cylinder...

Homework Statement A proton is fired at a nucleus containing Z protons and N neutrons, with a kinetic energy K. Show that the minimal distance r_0 = [(Ze^2) / 4pi*epsilon_0] * (1/K) Homework Equations E=(q/4pi*epsilon_0) * (r-r' / |r-r'|^3) The Attempt at a Solution I know that at...

I'm assuming it's the latter; that I can ignore Q2 and only count Q1. I'm still not sure how to do it though. Is |q| in E=k|q| / r^2 simply the value of Q1? Thanks!

Homework Statement I have 2 charges: Q1 = 300 uC located at (1, -1, -3) m Q2 = ?? uC located at (3, -3, -2) m Q1 feels a force from Q2 of F1=(8i - 8j + 4k) N 1. Find Q2 2. Find the expression of the E-Field at (3, -3, -2) m (at Q2) Homework Equations F=(k|Q1*Q2|) / r^2 E=(k|q|)...

There is a value of t for which: 25 - (20t+2.5(t^2) - 15t+3.75(t^2)) = 0 That is, 25 meters between cars - (total distance traveled by both cars) = 0 That value of t should be a bit more precise. I think? :) I think that comes up to having one of the car going towards the right (assuming...

I think I solved this whole thing but it seems a bit too simple. I think I might've missed a detail somewhere. This is the problem, followed by my steps: Homework Statement Two cars are about hit each other (face to face). The first car is doing 20m/s and decelerating at a rate of 5m/s^2...

Hello! I'm studying for a biology midterm coming up and I would really like to get an idea of the kind of questions that might end up on the exam. Most of my classes have old exams available online/at the library but for some reason the biology department doesn't allow the library to publish...

Is there any free book(s) available that has sets of exercises after each chapter? I'm looking for more practice material but most of the free content available online (the books I've found / the classes on iTunes U) only have theory, no practice problems. I'm glad to have access to all this...

I'm 22 and just starting, and a lot of people in the physics faculty are starting at age 25+. 19-20 is a pretty standard age to start you undergrad here in Quebec, Canada because of our education system so I wouldn't worry at all about this!

I wasn't aware of a Mac version of Notepad++! If so then it'd be worth checking it out then

For a beginner, XCode could be a bit overwhelming. For simple programs (using only 1-3 files) I prefer using Textmate & GCC. Although it doesn't have auto-completion it has syntax highlighting and amazing keyboard shortcuts. It's a shareware, but you can try it for free for a month, and it's...

Thanks for the link! I'll be looking over their review section and see if I can find something interesting. We have a pretty big planetarium here and I just found out they have an amateur astronomy club so I think I'll join. It's ~30$ for a year and gives you access to some of their equipment...

Hello! I'm not sure if this is the right section but it seems the best one for this question. I've been looking to buy a telescope just for fun and I'm surprised with just how many different options are available out there. I'm looking for something that's good for beginners since I've never...

Hello! I've been solving a few of these problems but I'm stuck on this one, trying to simplify one of the steps. Homework Statement Find dy/dx of: y = x(x^2 +1)^1/2 Attempt at a solution y1 = x (1/2)(x^2 + 1)^-1/2 * (2x) + (x^2 +1)^1/2 * 1 I get the the equation above but I have...

Hello! I'm trying to find the following limit: {\lim_{x \to 5}}\ {5-x \over {3-\sqrt{x^2 -16}} I tried 2 things Simplifying the bottom: 3-\sqrt{x^2-16} = 3-\sqrt{x^2-4^2} = 3-x-4 = -1-x But that doesn't help with what's on top... I also tried multiplying top and bottom by...