Frequency, Period and Waves

1. Aug 30, 2008

iamamn

Right, im new here and i am really stuck on my homework.
Wandering if you could help me :D lol
anyways,

a loudspeaker vibrates at a frequency of 256 herts to produce a note we call middle c.
(a) how many waves does it produce in one second
(b) how many waves does it produce in 1 minute.?

and also ...

when a stone is dropped into a pond the watr waves spread out and travel a distance of 4 meters in 2 seconds. what is the speed of these waves?

i know they might be simple to you, but i havent been taught how to do these ...
I got taught how to find out freqency and period, but i just cant figure out how to do these

YOUR HELP WILL BE APPRECIATED :D
xo

2. Aug 30, 2008

Hootenanny

Staff Emeritus
Welcome to PF iamamn,

Firstly, please don't write in large bold font, it makes your post difficult to read. Secondly, we have Homework Forums for dedicated homework assistance (but don't worry, a mentor will move it there shortly). And thirdly, when requesting homework help you are expected to show an attempted solution or at least outline your thoughts on the problem.

However, since you're new we'll let you off .

Can you tell me the definition of frequency, or more specifically one Hertz?

3. Aug 30, 2008

iamamn

OK. :D
Well the examples we got in school were:

if a wave has a frwency of 50Hz - whatt's its period?
and i came up with:

T = ?
F = 50hz
T=1/F
T = 1/50 = 0.02s

and if a wave has a period of 5z - what's its frquency?

F = ?
T = 5s
F = 1/T
F = 1/5 = 0.20 Hz

and frequency is the number of waves produced per second by the wave source. and measured in seconds.

I just cant figure it ot really ...

buut for the loudspeaker one is it 256hz for 1 second? and then for (b) times it by 60?

4. Aug 30, 2008

Hootenanny

Staff Emeritus
Correct. The frequency is simply the number of oscillations (or waves produced) per unit time. So a wave-source oscillating at 256 Hertz produces 256 waves per second. And of course one simply multiplies this number by 60 to obtain the number of waves per minute.

5. Aug 30, 2008

iamamn

AH! So simple really. i can't belive i couldn't get that :D.

So for the other question,

when the stone is dropped ...

Do i use the frequency solution to find that out? but if i do it doesn't really work out if its asking for speed of the waves.

would the anwser be 2 meters per second? by simply just "halfing" it? to get the number of waves per second?

6. Aug 30, 2008

Hootenanny

Staff Emeritus
No, for the next question you don't use the frequency method, but the solution is just as simple. Think about the definition of speed.

7. Aug 30, 2008

iamamn

Would the anwser be 2 m/s ?

:S

8. Aug 30, 2008

Hootenanny

Staff Emeritus
Indeed it would

9. Aug 30, 2008

iamamn

Well thank you very much Hootenanny :D
You have been a very big help to my homework and my knowledge :D
THANK YOU xo

10. Aug 30, 2008

Hootenanny

Staff Emeritus
It was a pleasure.