# Search results

1. ### Velocity of wave along a rubber cord

]Homework Statement You have a rubber cord of relaxed length x. It be- haves according to Hooke's law with a "spring con- stant" equal to k. You then stretch the cord so it has a new length equal to 2x. a) Show that a wave will propagate along the cord with speed...
2. ### Collision of a moving proton into a proton at rest (relativity)

I failed , sorry vela. The my ******* proffesor put this one test and he knew it was the only one i didnt awnser. Out of 30 homework questions he always puts 6 on the test and he puts the only one i didnt have. Oh well i will still get an A but i wanted 100% cause it makes him mad when someone...
3. ### Collision of a moving proton into a proton at rest (relativity)

I feel like a complete retard now...but i still can't see it. I did what you told me and i still can't see how the momentum cancels out.
4. ### Collision of a moving proton into a proton at rest (relativity)

yes i know what your saying: Kinetic energy energy of moving proton is K1=(gamma1-1)mc2 But this takes me back to the initial quetion i would have to solve for the velocity in the gamma to obtain the kinetic energy just in terms of mass and c2. Iam stupid sorry, iam not understanding at...
5. ### Collision of a moving proton into a proton at rest (relativity)

Sorry vela. I thought you mean start by energies and momentum to get velcoties. Ok i managed to obtain the mass in terms of the K1 using hte euation above and the third relavant equation. m=(pc)2 - K12/(2K1c2) i don't know if this will help. When you say the equations for conservation of...
6. ### Tomorrow i have a test, I with these questions

Q=mC C is a constant you can look up for water its different depending on which phase transition you are calculating. Q=mc(Tf-Ti) for when your raising the temperature c i think its 1cal/gC for water. Add all the Qs and viola
7. ### Collision of a moving proton into a proton at rest (relativity)

This is the only problem i have left unsolved before tomorrows test(which is verbatim from homework). I've tried solving for the velocities using the previously mentioned equations but no luck =/.
8. ### Special relativity: Lightning and Trains (no math involved)

Well that clears all my doubts. Thank you very much i just have to be carefull with my wording :D
9. ### Special relativity: Lightning and Trains (no math involved)

I got it! i think.. the proffessors train is larger than it actually it is if they are both measured at rest!. makes sense. Now I just have to figure how to make it work ... Is the students train going to even smaller than it actually it is from the proffessors point of view? or is...
10. ### Special relativity: Lightning and Trains (no math involved)

Homework Statement Consider the relativity of simultaneity: A student in a train at rest from his point of view and a professor in a train that is moving in the positive x direction from the student’s perspective. Two lightning of different colors will strike at opposite ends of the trains...
11. ### Collision of a moving proton into a proton at rest (relativity)

Well you have the proton at rest: E=mc2 K=0 p=0 The moving proton E1=K1+ mc2 p=(gamma1)mu whre u is the speed of the proton The blob: E2=K2+4mc2 p=(gamma2)mv where v is the velocity of the blob Equating any of teh energy/momentum equations together just seems like a big mess because...
12. ### Collision of a moving proton into a proton at rest (relativity)

Well if the proton is going fast enough to overcome the electric repulsive forces it would collide wouldn't it? that's how colliders work don't they? And i have never heard of 4 vectors sorry =/. And the velocities i got it from equating the total energies of the "reactancts" and...
13. ### Collision of a moving proton into a proton at rest (relativity)

Homework Statement A high speed proton collides with a proton at rest, two proton-antiproton pairs were created. That is some of the accelerated protons kinetic energy was enough to be converted into the mass of the new particles. If the proton-antiproton pairs move along together as a single...
14. ### Relativistic acceleration with integration problem

Thanks vela, I was trying that approach earlier but i can't solve that nasty integral, going to keep trying
15. ### Relativistic acceleration with integration problem

Thats what i was trying a=dv/dt then pass dt to the RHS to integrate and which also has a v=dx/dt which is where iam confused. And for tiny-tim's response Iam not seeing where your going with that... =f(v)dtdv? double integration?
16. ### Location of maximum desctructive intereference

one bump because I still haven't solved this and my test is this week =/. Thanks for the help
17. ### Relativistic acceleration with integration problem

Homework Statement Consider a spaceship that accelerates so that the passengers feel and acceleration equal to that of gravity of the earth’s surface, g. If the spaceship undergoes this acceleration for a time T, show that the final velocity is given by: V=c[1+(c/gT)^2]^(-1/2) Homework...
18. ### Location of maximum desctructive intereference

Homework Statement Two radio sources in the xy plane are in phase and emitting the same wavelength, λ. Their locations are at coordinates (0,0) and (3λ,0). Show that the largest value of y at which fully destructive intereference may occur at coordinates (0, y) is given by y=35λ/4...
19. ### String waves on a cable car and free falling.

hmm yea that's what i was thinking...Thanks a lot :)
20. ### String waves on a cable car and free falling.

nm! i don't have it now...iam stupid sine of 2pii is not 1 lol that sine term still bothering me...somehow i know i have to make the stuff inside the sine equal to pii/2.
21. ### String waves on a cable car and free falling.

wait wait! i have it just substitute back for v^{2} and which equals T/u and viola! tho there's a small problem...the negative sign... Thanks a lot tho man!

23. ### String waves on a cable car and free falling.

w = 2\pif where f is the angular frequency and k =\frac{2\pi}{\lambda} that would give you sin(2\pi(\frac{x}{\lambda} - ft)) by factoring a 2pii inside... still not seeing how the sine term is somehow related to the tension and linear mass density =/
24. ### String waves on a cable car and free falling.

Homework Statement You're riding a cable car from Bogota up to Monser- rate. During your ride there is a small earthquake that sends vertical, transverse waves propagating along the cable. The cable's tension is T, its linear mass den- sity is u, and the wavelength of the wave is...
25. ### Wave propagation along a rubber cord.

! I understand part a completly. I just set it up like df=kdx and did the integral from x to 2x...The math makes more sense now...Thanks! Sadly iam still stuck in part b.
26. ### Wave propagation along a rubber cord.

shameless bumb :( still can't solve it.
27. ### Wave propagation along a rubber cord.

Homework Statement You have a rubber cord of relaxed length x. It be- haves according to Hooke's law with a "spring con- stant" equal to k. You then stretch the cord so it has a new length equal to 2x. a) Show that a wave will propagate along the cord with speed...
28. ### A wave speed of a hanging chain

Ahhhh i finally got it. THANKS ALOT. My problem was that i didnt understand the concept well enough to understand that tension varies with the speed. Was easier than i thought.
29. ### A wave speed of a hanging chain

Yes, I've tried that approach but i think the awnser lies in the differential equation that i posted which is where the velocity of the wave in a string is derived from. Unless iam overcomplicating myself and iam not seeing something. Because i know that T=uLg and the time would be L/v but i...
30. ### A wave speed of a hanging chain

Homework Statement Problem 5 from: http://www.swccd.edu/~jveal/phys274/images/hw01.pdf in case you don't understand my text. A chain of linear mass density u, and length L is hang- ing from a ceiling. There is a wave moving vertically along its length. a) Is the propagation speed...