PHYSICS help plz!!!! Due 2morrow!!!

[miyuki9]

I'm learning about waves, frequency, vibration, beats,... Then I have to answers a bunch of question from the worksheet...Can someone plz help me to answer the question below... Thanks
1)Why will marchers at the end of a long parade following a band be out of step with marchers nearer the band?
2)What 2 physics mistakes occur in a science fiction movie when you see and hear at the same time a distant explosion in outer space?
3)If the handle of a tuning fork is held solidly against a table, the sound becomes louder.
Why? How will this affect the length of the time the fork keeps vibrating? Explain using the LAW OF ENGERGY CONSERVATION.
4)Suppose a piano tuner hears 2 beats per second when listening to the combined sound from her tuning fork and the piano note being tuned. After slightly tightening the string, she hears 1 beat per second. Should she loosen or shoud she further tighten the string?
I think the answer for this one is that she should loosen the string... but I'm not exactly sure and don't know why..." Plz explain to me. Thanks

[schwarzchildradius]

All of these questions can be answered here but this should go in homework help.
In any case,
1) assumes that each marcher is in step with the marcher in front. think about it.
2) this one is very easy. to answer, answer smaller questions: how does sound propagate? How long does it take for sound to reach an observer ?
3)the sound energy is conducted into the table. The energy emmitted by the fork is equal to the energy input into it by the strike.
4) beats occur when wave nodes coincide. there sould be a wave equation you can find, and analyze. Also, picture it in your mind.

[Alexander]

Quite simple problems Mi, try to solve them yourself. For #1,2 think of sound in air as simply of N2 molecules bumping into neighboring molecules, them - into their neighbors and so on. For #3 think of fork atoms bumping into table atoms, table atoms - into their neigboring table atoms, etc (and also table atoms bumping into N[sub]2[/sub molecules]. For #4 think of differences and proportions. If one step to the right makes change from 2 to 1, then should you step to the right or to the left to make change from 1 to 0?

[miyuki9]

More explaination plz, I'm confused

[BoulderHead]

Don't ask so many questions at the same time...or wait until the night before to do your homework! [:D]

Take number 1;

Remember your other problem with the sound from the hammer taking one second to arrive? What do you suppose might happen if a really long line of marchers are all stepping to the beat of a tune that is comming from the front of the column, for example?

[schwarzchildradius]

you have to have a text with equations, dont you?
basically,
v=λf
where λ is the length between the crests of the waves
where f is frequency, or amount of time passing between crests of the waves. frequency = 1/period, or f = 1/T,
v = change in x/change in time
you can rearrange algebraically, of course.
beats occur when you have two waves, and one wavelength of them is an integer multiple of the other wavelength.
Try one, they are easy.