# Recent content by PiRho31416

1. ### Pushing force with friction

Simon, Thanks so much! :) Adrian
2. ### Pushing force with friction

I just want to check to see if I did the problem correctly. A person pushes a 2.0 kg box across a flat, horizontal surface with a force of 5.0 N for 4.0 m. Determine the acceleration of a box if the friction coefficient is 0.2. Determine the acceleration of the box if the friction coefficient...

4. ### Laplace Transform

Oh crap. The negative sign! Sorry it was late last night and somehow I thought he was saying \mathcal{L}\{y(t)\}\neq Y Sorry about that. He even says it's +4y not -4y. Geez :-(
5. ### Laplace Transform

Pretty sure it is.

Thanks! Duh!
7. ### Laplace Transform

[Solved] Laplace Transform Homework Statement \frac{d^{2}y}{dt^{2}}+4y=sin(t),\quad y(0)=0,\quad\frac{dy}{dt}(0)=0 Homework Equations Laplace transform is defined as: \mathcal{L}\{f(t)\} = \int_{-\infty}^{\infty}f(t)e^{st}dt The Attempt at a Solution...
8. ### Inflection point conc up/down

Thanks for correcting me. It was really late last night :-)
9. ### Inflection point conc up/down

Yup. No problem. Feel free to ask. I'm struggling with math myself :-)
10. ### Inflection point conc up/down

As you mentioned f''(x)=-6x-6=-6(x-1). So there is a root at x=1. Let's look at when f''(0) and when f''(2). f''(0)=-6(0)-6=-6 which means concave up. f''(2)=-6(2)-6=-12-6=-6 which means concave down.
11. ### Inflection point conc up/down

Notice my f(x) is different from your problem. I'm making up a whole new problem. I was hoping you take take my example and figure out your problem.
12. ### Inflection point conc up/down

Let's take the last part of your equation for an example. f(x)=-3x^{2}-4x-2 f'(x)=-6x-4 The root of the first derivative is when x=-2/3. So let's plug in -1 and 0 since it's to the left and right of the critical point. f'(-1)=-6(-1)-4=2 So from -\infty to -1 it is increasing. Now let's plug in...
13. ### Inflection point conc up/down

Sorry latex fail :-P It's fixed now. If you need more examples, feel free to ask.
14. ### Inflection point conc up/down

It is concave down when the second derivative is negative. It is concave up when the second derivative is positive. Let's say f(x)=x^{3}. f'(x)=3x^{2} f''(x)=6x First derivative tells you whether the function is increasing or decreasing. Second derivative tells you the concavity. If the...
15. ### LaTeX How I can use a vertical bar to represent evaluation in LaTeX

I'm using lyx and I'm having difficulty trying to find the code for this vertical line. Any suggestions? I use the | but it's extremely small.