# Search results

1. ### Finding Constants to Solution Given 2nd Order, Nonlinear DE

Alright, I ended up with A=+/- 1 and B=1/sqrt(2).
2. ### Finding Constants to Solution Given 2nd Order, Nonlinear DE

Ahhh yes. I understand! Thank you very much :)
3. ### Finding Constants to Solution Given 2nd Order, Nonlinear DE

I keep getting that phi is zero.
4. ### Finding Constants to Solution Given 2nd Order, Nonlinear DE

The second derivative is phi''=-2AB^2tanh(Bx)sech^2(Bx)= -2AB^2tanh(Bx)+2AB^2tanh^3(Bx) and so tanh(Bx)[2AB^2-A]+tanh^3(Bx)[-2AB^2+A^3]=0
5. ### Finding Constants to Solution Given 2nd Order, Nonlinear DE

d^2phi/dx^2= -2AB^2tanh(Bx), correct? Now I have gotten the equation tanh(Bx)[2AB^2-A+A^3tanh^2(Bx)]=0 I set 2AB^2-A+A^3tanh^2(Bx)=0 tanh(Bx)= sqrt[2B-1]/A But now what? Was I supposed to change the tanh^2(Bx) into 1-sech^2(Bx)?
6. ### Finding Constants to Solution Given 2nd Order, Nonlinear DE

Homework Statement Okay, here's the deal: I have been given a second order nonlinear differential equation, and I have also been given the general solution with constants A and B. I am supposed to find the constants A and B. The solution represents a fermion at rest, since the solution does...
7. ### Recommendation Moral Dilemma

Hello! I am wondering if anyone can help me decide what to do about this problem. I'm at a college majoring in physics, and I'm almost done with my two years. I'm applying to different universities,and I have a professor that wishes to write me a recommendation for when I transfer. He asked me...
8. ### Is the Derivative of a Function a Differential Equation?

I am talking about first order ones.. I don't know how to solve second order ones.
9. ### Is the Derivative of a Function a Differential Equation?

Is the derivative of a function a differential equation? I guess it would be because it involves a derivative, right? Would the solution to the equation just be the original function? Is solving a differential equation just another way of integrating? Like with finding solutions of separable...
10. ### Rolling Ball and Proportionality Between Distance and Time

Thanks a lot. I didn't know it was so complicated. Thanks again.
11. ### Rolling Ball and Proportionality Between Distance and Time

Homework Statement A ball starts from rest and rolls down a hill with uniform acceleration, traveling 130m during the second 6.0s of its motion. How far did it roll during the first 6.0s of motion? Homework Equations I guess: v=v(0)+at v^2=v(0)^2+2ay x=x(0)+v(0)t+0.5at^2 The Attempt at...
12. ### Two values for m for which a line is tangent to a parabola

Ouuuu interesting. Thank you :)

Thanks!
14. ### Two values for m for which a line is tangent to a parabola

Homework Statement Hi! I am doing some problems to practice for a math competition, and I'm wondering if I did this correctly. I don't really have an answer sheet, so I have no way of knowing whether I'm right. If you would please review it, that would be cool! It reads: There are...
15. ### Schools French Universities For Physics

Hello! I'm wondering if anyone knows any universities in France that have a great physics department. I'm currently in my second year of college getting my associates degree, and I'm looking at options in France for my bachelors. My French professor is always talking about French...
16. ### Does it matter if L + epsilon is not in the range of the function?

Uhm, okay. So... who is right? I don't quite understand what L-ε < f(x) < L -ε means. Do you mean L - ε < f(x) < L + ε ?
17. ### Does it matter if L + epsilon is not in the range of the function?

Homework Statement Use a graphing calculator to find \delta when 0<|x - \pi/2|<\delta and |sin(x) - 1|<0.2 Homework Equations I don't think there are any other than the format of the previous information: 0<|x-a|<\delta and |f(x)-L|<\epsilon The Attempt at a Solution Okay...
18. ### Finding the point where the net electric field is zero

Oh, okay! Thank you very much! :)
19. ### Finding the point where the net electric field is zero

Homework Statement The question wasn't really written down. It was a question asked after an explanation, and it really wasn't straightforward. I'm going to try to make it into a intelligible thing. If there is a +3 charge and a -1 charge at a distance from one another, where to the right...
20. ### Finding a Coefficient in an Expansion (n-j is negative?)

Oh my god! Yes! I see! Thank you! I wonder why my teacher did it like that, though. Thanks! :)
21. ### Finding a Coefficient in an Expansion (n-j is negative?)

In that case, j would be just four, right?
22. ### Finding a Coefficient in an Expansion (n-j is negative?)

Hmm well.. that's how my professor did it. So after trying multiple times with different values for n and j, I got the right one. I ended up using n=7 and j=4. At first I tried n=14 and j=8. Nope. Then, I tried n=14 and j=4. Nope. Then, I tried n=7 and j=4! It worked... I'm still not so sure...
23. ### Finding a Coefficient in an Expansion (n-j is negative?)

Homework Statement Find the coefficient of x8 in the expansion of (x2-3)7 Homework Equations This one: (n n-j) an-jxj The Attempt at a Solution Hi! Well, I know that x= x2 a= -3 n= 7 and apparently, j=8. This is what confuses me. n-j is a negative number.. how would...
24. ### History of Physics

Thank you so much :) I'm going to check it out :)
25. ### History of Physics

Hello! I've recently begun to read a lot of nonfiction books. I'm currently reading a book about stories told by Richard Feynman about his amazing life. It's hilarious and so clever. I would absolutely LOVE to read a book on the history of physics! I think it's really fascinating. Could...
26. ### Tension and Acceleration with a Pulley and Two Masses

I mean, I think it would be equal.. but I'm not sure. Apparently it would be zero if the string has negligible mass.
27. ### Tension and Acceleration with a Pulley and Two Masses

Homework Statement If there is a mass on a frictionless table connected by a string to another mass hanging from a pulley off the side of the table, is the net force on the string zero? Is the force of tension equal on both sides if the system is accelerating? Would both objects accelerate...
28. ### Pre-Calculus and Trigonometry

Hmm... Everyone I know at my school avoids math like if it were a disease. If I take them separate, I'd pay around a hundred dollars more. I'm guessing that wouldn't be much of a problem. Yeah, I totally need to take them. I'm thinking of taking both separately. I need to take them in the...
29. ### Pre-Calculus and Trigonometry

Hi! I am currently taking a math class called college algebra. Here's the little description thing: MAC1105 - This course introduces the student to the concept of functions and their graphs. Students will graph linear, quadratic, rational, exponential, logarithmic, radical, power, and...
30. ### Why do people say that the person would be weightless?

I don't understand that, but hopefully in the future I will.. I guess if the object is on the surface I would just use mg, but if the object is far from the surface I'd use GmM/r^2 ?
31. ### Why do people say that the person would be weightless?

Okay I just tested it with a 60 kg person and both were the same!
32. ### Why do people say that the person would be weightless?

So will the weight using mass times the local acceleration of a person on the surface of the Earth be the same as the weight found using the universal gravitation? How would I know which to use?
33. ### Why do people say that the person would be weightless?

Wow.. Just.. Yep. Thanks
34. ### Why do people say that the person would be weightless?

But there really is gravity, right? Or is there no gravity because he has no way of telling that there's no gravity? Is that what 'reference frames' refers to?
35. ### Why do people say that the person would be weightless?

Ooh, okay. So it's not really weightless.. it just feels like it is. So a scale would read zero but only because there's no normal force? Wait but in space there is gravitational force.
36. ### Why do people say that the person would be weightless?

Homework Statement If someone is in an elevator that is in free fall, why do people say that the person would be weightless? Wouldn't the person weigh mass times the gravitational acceleration?
37. ### Finding Gravitational Acceleration from a Slope

Omg. So the answer for a=9.48 m/s^2 right?? I'm starting to doubt everything...
38. ### Finding Gravitational Acceleration from a Slope

oh my. i almost died. i thought it was right and did my assignment based on it since no one had answered. thank you soooo much!
39. ### Finding Gravitational Acceleration from a Slope

The height is the independent variable, right?..
40. ### Finding Gravitational Acceleration from a Slope

So how would I put that into a= 2y/t^2 ? Can't I put it in and do 2*(1m/0.211s^s)?
41. ### Finding Gravitational Acceleration from a Slope

Wait. What? So is 0.211s^2/m equal to 1m/0.211s^2? :/ So would I have 2m/0.211s^2 ?
42. ### Finding Gravitational Acceleration from a Slope

Okay. I think I get it a little after thinking about it for a while. I used that equation and I moved it around to get a= 2y/t^2 If I were to put the slope there, would it work?? Do I have to somehow make the t^2 on the top?? Please help. is the slope the same thing backwards?? oh my god if...
43. ### Finding Gravitational Acceleration from a Slope

I don't know. I really don't know how to change it. I have no clue and I can't even think of anything close because I simply don't know. I can't come up with something out of nothing.
44. ### Finding Gravitational Acceleration from a Slope

oh. my. god. Yeah, I didn't realize that. I still don't get it, though. I have the slope of the line.. and I have different heights, but I only need one answer for the acceleration that counts for everything.
45. ### Finding Gravitational Acceleration from a Slope

How could that even be? I don't even know the initial velocity.
46. ### Finding Gravitational Acceleration from a Slope

...? Does that mean y=y0+v0t+1/2 at2 That's the only one I know that has initial height..
47. ### Finding Gravitational Acceleration from a Slope

Uhm, I don't understand.. So we basically did this in class and we set it up and timed it. We did it multiple times with different heights and then we graphed the data. But it was a quadratic relationship so we were told to use the average time to find time squared and then graph time squared vs...
48. ### Finding Gravitational Acceleration from a Slope

Homework Statement I have a graph of time squared vs. height. It shows the relationship between the height of a ball and how long it takes for it to fall, squared. I don't have this in the form of a question, but I need to use the slope, which is 0.211 s^2/m, and turn it into a value for...
49. ### Deriving Projectile Motion Equations

Really!? So I am right.. I was told by someone that part C was wrong.. o_o
50. ### Deriving Projectile Motion Equations

Homework Statement A projectile is fired from ground level at time t=0, at an angle of θ with respect to the horizontal. It has initial speed V0. Part A Find the time it takes the projectile to reach its maximum height. Express in terms of V0, θ, and g. Part B Find the time at...