# Search results

1. ### Strain Gage Errors

Homework Statement What are the potential errors in measuring strain with strain gages? How can these errors be minimized? The Attempt at a Solution In my class notes, I have the four Errors. 1-Gage mounting (glue thickness & flex) Use a thin layer of glue and make sure the layer is...
2. ### How many bits should be employed to obtain a resolution

Wow, thank for the quick reply. I know that, but don't you times it by 10 V? Isn't the units for resolution volts? I assumed when they said "resolution of 0.01%," I assumed this was .01% of the full scale voltage. Is that wrong to assume? Should resolution just equal .0001? Then N= 16.6 = 17...
3. ### How many bits should be employed to obtain a resolution

Homework Statement An A/D converter is to operate with a full-scale voltage of 10V. How many bits should be employed to obtain a resolution of 0.01%? Homework Equations Resolution = Full Scale voltage / (2N - 1) The Attempt at a Solution .01% * 10 V = .01/100 * 10 V = .001...
4. ### Statics homework problem

Homework Statement http://img843.imageshack.us/img843/5370/helpxd.jpg [Broken] Homework Equations Sin law The Attempt at a Solution I got to: F1/sin(105) = F1u/sin(45) = F1v/sin(30) I get F1u = - 219 and F1v = 254.5.... It says it is wrong, not sure what I did.
5. ### Intergration my parts. Reduce.

Homework Statement S P^4 e^-P DP Homework Equations My parts. The Attempt at a Solution I know you can do u = P^4, and DV = e^-P Then, you get du = 4P^3 dx and V = -e^-P -P^4 e^P + S 4P^3 e^-p dx Now, I can just repeat that for the intergral until I get to were the P...
6. ### Expanding the binomial

Homework Statement by expanding the binomial show that ( (Sqtroot(3)/2) + (1/2)i )^4 = ( (-1/2) + (sqroot(3)/2)i ) The Attempt at a Solution I'm stuck, I now ( (Sqtroot(3)/2) + (1/2)i )^4 = ( (9/16) + (1/16)i ) But that's all I got, don't know the next steps.
7. ### Convert the equation to a first order system.

What reply box? ______________________________________ Now, I'm having troubles again. dv/dt = -3v -2y dy/dt=v A = [-3 -2 ] [1 0] Det: [-3-Lamba -2 ] = 0 [1 0-lamba ] (-3 - lamba)(0-lamba) -(-2)(1) = 0 Lamba2 -3 lamba + 2 =0 (lamba...
8. ### Gaussian Elimination Matrix

Homework Statement Using Gaussian Elimination: 3x - 2 y = 5 6x-4y =7 The Attempt at a Solution [ 3 -2 5] [6 -4 7] * top row by 1/3 [1 -2/3 5/3] * Top row by -6, add to bottom row: [0 0 -3] So I get this: [1 -2/3 5/3] [0 0 -3] How can 0y equal -3?
9. ### Convert the equation to a first order system.

Homework Statement Convert the equation to a first order system. d^2y/dt^2 + 3dy/dt + 2y = 0 The Attempt at a Solution Set d^2y/dt^2 = dv/dt dy/dt = V So, I now have: dv/dt + 3v + 2y = 0 Now, i'm not sure what to do with that Y, In my notes we only did examples with...

Thank you.
11. ### Find all Equilibrium points for the following systems.

Homework Statement Find all Equilibrium points for the following systems. B. dx/dt = 5x - x^2 - 3xy dy/dt = 8y - 3xy - 3y^2 The Attempt at a Solution 0 = x(x + 3y - 5) 0 = y(y + x - 8/3) Equilibrium points: (0,0) but I can't find anymore? is (0,0) the only one?
12. ### How to maximize a function?

Yeah, I caught that. Thank you though.
13. ### How to maximize a function?

Nevermind, I got it....56.25lbs...
14. ### How to maximize a function?

I think I set y(t) to 0. If this is the case, I get: 0 = -100e^(-1/20t) + 150e^(-1/40t) How do I get rid of the e's? I'm not sure how with the numbers is front. Without the numbers in front I know I could rise them to ln.
15. ### How to maximize a function?

Homework Statement http://img262.imageshack.us/img262/678/im000724.jpg [Broken] Uploaded with ImageShack.us The Attempt at a Solution http://img843.imageshack.us/img843/5651/im000726.jpg [Broken] Uploaded with ImageShack.us I got all the way to g, but I don't know how to...
16. ### Intergrating Factor - dy/dt = -2ty + 4e^-t^2

oh, yeah... I meant 4t + c......So the whole answer is y(t) = {4t + C}/e^{t^2} (The e^{t^2} is under both).....Yeah, I second guess myself way too much. Most the time, after I ask for help, I realize how easy a problem was and can't believe I ask for help.
17. ### Intergrating Factor - dy/dt = -2ty + 4e^-t^2

int_/ 4*e^{t^2} / e^{t^2} dt Then, the e^{t^2} cancel out and you are left with int_/ 4 dt which is just 4t. Is this right?
18. ### Intergrating Factor - dy/dt = -2ty + 4e^-t^2

Would the 4 go down to? Like this: e^{t^2} / 4e^{t^2} Wouldn't that leave you with 1/4?
19. ### Intergrating Factor - dy/dt = -2ty + 4e^-t^2

Homework Statement Solve the differential equations [Find the general solution y(t)=KYh(t) + Yp (t)]. Use the method of finding the integrating factor. dy/dt = -2ty + 4e^-t^2 The Attempt at a Solution S = intergrat dy/dt = -2ty + 4e^-t^2 dy/dt + 2ty = 4e^-t^2 P(t) = 2t b(t)...
20. ### Dy/dt = sin^2 y ebilibrium

Thanks, that make senses. So basically the equilibrium points are the same as sin y. -2pi, -pi, 0, pi, 2pi....etc but they are all nodes due to being always positive because sin^2 y = 1-cos^2 y.
21. ### Dy/dt = sin^2 y ebilibrium

I know what a sink, source and node are. Sink, both sides are going to it. Source, going away, node is both. Don't you have to put it in your calculator to see what they are doing between equilibrium's?
22. ### Dy/dt = sin^2 y ebilibrium

After I find the equilibrium points I have to determine if they're a sink, source or a node. Since I can't put it in my calculator, how do I determine that? Are they the same as sin y or the opposite?
23. ### Dy/dt = sin^2 y ebilibrium

Thanks, I was kind of thinking that. There was just no way for me to put it in my calculator to check.
24. ### Dy/dt = sin^2 y ebilibrium

Homework Statement I need to find the equilibrium solutions dy/dt = sin^2 y The Attempt at a Solution I don't know what to do with the sin^2. If it was just sin, it would be easy, 0, pi, -pi, 2pi, -2pi.....etc...... But it's not, I have a Ti-84 plus calculator. So, i don't...
25. ### Euler's Method - dy/dt = y^2-4t

Sweet, Thanks.
26. ### Euler's Method - dy/dt = y^2-4t

I think, I just started putting the t's in for t and the y's for y.... So for the first line I got: K: 0 t:0 y:0.5 dy/dt(t,y) = .25 Change in t*dy/dt(t,y) = .125
27. ### Euler's Method - dy/dt = y^2-4t

Homework Statement dy/dt = y^2-4t - y(0) = 0.5 - 0 <_ t <_ 3.0 - Change in t = 0.5 I have to use Euler's method to make a table, but I'm not sure how to handle the t. I have only done it with y's and no other variables.
28. ### Dp/dt = 4p-3p^2-p^3Diff. Equation.

sounds good. Thanks, you have been a lot of help :)
29. ### Dp/dt = 4p-3p^2-p^3Diff. Equation.

I don't know the answer, but it does need to be P (t) = F(t). Because after we are done, we need to use a few initial conditions.... P(0)= 3, P(0)= -1/2, P(0)= -2.
30. ### Dp/dt = 4p-3p^2-p^3Diff. Equation.

How do you handled after this point though. The other I knew how to do, just made a few little errors. I know, LN A - LN B = LN A/B I also know, 1/A LN |B| = LN Aroot of B Once I get them all to LN Some-Root B, I can get them all to the same LN. and will I take the e of both sides the LN is...