# Explaining the law of conservation

#### 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

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#### Tom Mattson

Staff Emeritus
Gold Member
miyuki9,

We have a policy regarding helping people with their homework at PF:

We're happy to help, but we will not do it for you.

You will get much more feedback if you show us how you start the problems and where you get stuck. We will then help you through the rough spots. You will also probably have better luck by posting in the Homework Help forum. Most people come to the Physics forum to talk about physics that interests them.

Regards,

#### dav2008

Gold Member
1)Huh? Um...im not sure what this is asking...

2)Sound needs a medium to travel through...space is almost a vaccumm...

Compare the speeds of light and sound..

For number 4, think about the fact that the beat frequency which she hears is the difference between the two notes played.(i.e. if the two notes were 500 and 502 hZ then the heard beat frequency would be 2 hZ) Tightening the strings would raise the frequency, and loosening would lower it

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