physics hmwk...pllzz help??...?

Question

To demonstrate standing waves, 1 end of a string is attached to a tuning fork w/ frequency 120Hz. The other end of the string passes over a pulley & is connected to a suspended mass M. The value of M is such that the standing wave pattern has 4 "loops." The length of the string from the tuning fork to the point where the string touches the top of the pulley is 1.20m. The linear density of the string is 1.0x10-4 kg/m, and remains constant throughout the experiment.
(a) Determine the wavelength of the standing wave.
(b) Determine the speed of the transverse waves along the string.
(c) The speed of the waves along the string increases w/ increasing tension in the string. Indicate whether the value of M should be increased or decreased in order to double the # of loops in the standing wave pattern. Justify ur answer.
(d). If a point on the string at an antinode moves a total vertical distance of 4cm during 1 complete cycle, what is the amplitude of the standing wave?

http://courses.ncssm.edu/winborne/linked%20docs%20and%20such/Practice%20Problem%20Waves%20on%20a%20String.doc

this link has the ques on it along w/ the picture that it came w/....i hope u'll be able to open it.. any help wud be greatly appreciated...thank u soo much!!

http://courses.ncssm.edu/winborne/linked%20docs%20and%20such/Practice%20Problem%20Waves%20on%20a%20String.doc

http://courses.ncssm.edu/winborne/linked%20docs%20and%20such/Practice%20Problem%20Waves%20on%20a%20String.doc

Answer 1

Draw a diagram of your set-up. A tuning fork is difficult to use as its amplitude decays too quickly (unless electrically driven).
You usually use an electrical vibrator and a singnal generator.
Although the point where the string is attached is moving, as far as the standing wave is concerned it is a fixed point - so it looks as though there are 1 2 3 4 etc fans on the string rather than 1/2 fans. Set up the expt and check for yourself.

Now:
1) Identify one cycle of the standing wave (a Sine Wave with 1up 1 down part) You will see there are 2 standing on your string (ie 4 half waves). So the wavelength is half the string's length.

2) Get the speed from: c = f * wavelength.

3) for a fixed frequency : if the speed increase then the wavelegth (ie the distance moved in 1 period) also increases. You need to halve the wavelength to double the standing wave pattern.

4) If the complete distance is 40mm; and we use the formula:
y = aSin(wt), The Sin(wt) has extreme values of: +1 and -1 so the value of 'a' is half the total displacement.

Answer 2

Just more physics jargon ... I am not even sure if this is correct anymore ... Photons and gluons are strictly massless. They are the gauge fields of unbroken symmetries (unlike the weak vector bosons). Due to the strong force and the self-interactions of the gluons (the strong force originates from a non-Abelian group -- so there is self interaction among the gauge fields -- the gauge fields themselves are charged), there may be gluon condensation and the condensation appears massive. As they are massless, they do not directly interact with Higgs boson at the tree-level. At higher-loop levels, there are interactions because you can have all sorts of virtual particles (i.e. particles that are not 'on-shell'). The same likely goes for the interactions with gravitons (the particle interpretation of the gravitational field). Photons curve around large bodies. Photons can not escape black holes once they are in the event horizon of the black holes. However, those two things are somewhat independent, unless the curvature of the photon trajectory is induced by the black hole.