# Search results

1. ### Axially Loaded Member and Tensile Stress oh so lost

Homework Statement "The axial load for a given test sample carries 1590 N. Calculate tensile stress at sections (1) and (2) assuming the sample thickness is 5mm. (Rectangular cross section). http://img208.imageshack.us/img208/121/tensilestressby1.th.jpg [Broken] Homework Equations...
2. ### Statically Indeterminate Stepped Bar Problem

I've been having difficulty with this problem for the past 5 hours. I am understanding some part, but I can't get the final answer. http://img223.imageshack.us/img223/1103/1015zz1.th.jpg [Broken] This is what I got so far: EFx = Ra + Rb - P = 0 Ra + Rb = P Sab = Sac + Scb =...
3. ### Equilibrium of Coplanar Force Systems HW Problem

I've been having trouble with the homework problem attached as an image. I need to find the tension in the cable and the reactions at A (Ay and Ax). In previous homeworks, I've been able to find the reactions at similar points A by finding the moment about A around a few other points. Now...
4. ### Specific Heat of aluminum Problem

"A piece of aluminum (specific heat 910 J/kg-C) of mass 200g at 80.0 deg Celcius is dropped into a styrofoam cup filled with 100mL of water at 20.0 deg C. What are the final temperatures of the water and the aluminum?" This is what I got: I figured out the amount of heat energy transferred...
5. ### Uniform Circular Motion roller coaster

This is another problem a buddy of mine and I cannot figure out if our life depended on it. Here's the question word for word: A roller coaster track has a hill with a circular curve of radius 20 m. Find the speed of the roller coaster at the top of this hill. Started by drawing a picture...
6. ### Nonequilibrium Applications of Newton's 2nd Law Problem

I along with a buddy of mine in the same course have been trying to figure out the following question. We spent at least an hour and a half to two hours and nothing makes sense. Any help would be greatly appreciated. Here's the question as it's written: One way to measure the acceleration...
7. ### Write # as a ratio of two integers

Problem: Write the number 3.1415999999999... as a ratio of two integers. In my book, they have a similar example, but using 2.3171717... And this is how they solved that problem. 2.3171717... = 2.3 + (17/10^3) + (17/10^5) + (17/10^7) + ... After the first term we have a geometric series...
8. ### Fibonacci Sequence so confused

My professor really threw a curve ball at me the other day with this problem, and unfortuneately, I have no idea where to begin. Any help would be greatly appreciated. In the following problem, all the n's are subdomains of the leading coefficent, along with the f#. f(sub 0), f(sub 1)...
9. ### Testing for Convergence

We just learned Alternating Series, but I am still unsure of the procedure. A couple of problems in the book have stumped me, and I need to test them for convergence. 1. Sum n=1 going to infinity of [cos(n*pi) / (n^(7/8))] 2. Sum n=1 going to infinity of (-n/5)^n I am really lost, I'd...
10. ### Doomsday Equation

Let c be a positive number. A differential equation of the form: dy/dt = ky^(1+c) where k is a positive constant, is called a doomsday equation because the equation in the expression ky^(1+c) is larger than that for natural growth (that is, ky). (a) Determine the solution that satisfies...
11. ### What is the half-life of radon-222?

After 3 days a sample of radon-222 decayed to 58% of its original amount: a) what is the half-life of radon-222? b) how long would it take the sample to decay to 10% of its original amount? check my answers please: a) m(t)=mo*e^kt t = 3 and m(t)=.58mo 0.58mo = mo*e^3k ln(.58)...
12. ### Trigonometric Integrals

I've been able to do all of them up until these two: 1) \int x\cos^{2}x dx and 2) \int from -\pi to \pi of \sin^{137}x dx I've been using half angle formulas where (cos x)^2 = (1/2)(1 + cos 2x) and (sin x)^2 = (1/2)(1 - cos 2x) I just can't figure those two out. Any help...
13. ### Area bounded by curves

This is the problem: find the area of the region bounded by the curves f(x) = x^2 + 2 and g(x) = 4 - x^2 on the interval [-2,2] I did the whole integral from -2 to 2 with (4-x^2) - (x^2 + 2) dx because the graph of g(x) is on top between the region bounded. But from my drawing, the points...
14. ### Integrals on exam I couldn't answer

On a recent exam I took, these integrals came up and I was unable to answer them correctly: \int \frac{2}{(x-1)^2+1} dx and \int \frac{2}{\sqrt{1-(x-1)^2}} dx I had absolutely no idea how to solve those 2 equations and my professor decided not to go over any of the problems...
15. ### Equation of the tangent line

I need to know how to find the equation of the tangent line to the graph of the equation y = xe^(1/x^2) + ln(3 - 2x^2) at the point (1, e). Admittedly, I have no idea at all what the question is asking for and I don't have the slighest clue on how to solve this question. Any help will be greatly...
16. ### Derivatives of natural logs and exponents

The problem I have is to find the derivative of the function: f(x) = (ln x)^x I know the derivative of ln x is 1/x, but the exponent is throwing me off. Can anyone offering any help? Thanks alot