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Frequency Equation

by celect
Tags: equation, frequency
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celect
#1
Jun21-05, 03:39 PM
P: 43
If I'm given v=50 sin(5000t)
how do I determine the frequency or amplitude?

Can someone direct me to a source?
thank you
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Delta
#2
Jun21-05, 04:01 PM
P: 101
http://www.physicsforums.com/showpos...07&postcount=5
celect
#3
Jun21-05, 08:05 PM
P: 43
do I take the sin of 50 then times that by 1/5000t?

EvLer
#4
Jun21-05, 09:45 PM
P: 460
Frequency Equation

just match your equation against what's in the link.
amplitude value precedes "sin(...)"

hint: phita (phase angle) is zero in your case
willib
#5
Jun22-05, 02:30 PM
P: 228
50 is your amplitude
5000 is your radian frequency in rad/sec
celect
#6
Jun22-05, 04:19 PM
P: 43
[itex]Vs = A*sin({\omega}t + {\phi})+C[/itex]


this formula states Vs =

Using the information I'm given

50 * sin(wt + 0) + C

is that the sin of 5000t
I'm confused on this I never used this type of equation before.
Delta
#7
Jun22-05, 05:13 PM
P: 101
Compare your equation

[tex]V = 50*sin(5000t)[/tex]

with

[tex]Vs = A*sin({\omega}t + {\phi})+C[/tex]

You can see that [tex]A[/tex] is 50 and [tex]\omega[/tex] is 5000. [tex]\Phi[/tex] and [tex]C[/tex] are zero.

As shown in my definition, [tex]A[/tex] is the amplitude and [tex]\omega[/tex] is equal to [tex]2{\pi}f[/tex]

So you can therefore determine the amplitude value and with a little calculation the frequency as well.
celect
#8
Jun22-05, 05:40 PM
P: 43
Iím really struggling here, if A = 50 and wt = 5000

If I want to know freq should I take the sin of 50(0.7666) and then multiply that by 5000


I have 10 problems I need to lean how to use this equation.
LeBrad
#9
Jun22-05, 07:30 PM
LeBrad's Avatar
P: 212
Sine is really important and something you should know well. If you have a graphing calculator, I would suggest plotting a bunch of [tex]A\sin(\omega t+\phi)+C[/tex] equations to see how the graph changes as the parameters change.

Sine itself can never get bigger than 1, and the things inside the sin can never change the height of the graph. [tex]\omega[/tex] and [tex]\phi[/tex], which go inside sin, only change the spacing and position with respect to the t axis. [tex]\omega[/tex] is the frequency, or how frequently the curve goes from top to bottom. [tex]\phi[/tex] just shifts it left and right on the time axis.

Since things inside sin don't change the height, that means only A and C can affect the position on the y axis. Since plain sin has a maximum value of 1, the maximum of A*sin will be whatver A is. Then if you add a C term, that just shifts the whole thing up or down on the y axis.

The frequency is [tex]\omega[/tex] itself, and the amplitude is A itself. There's no need to take the sin of anything or multimply anything. You're just identifying parameters in the equation.
celect
#10
Jun22-05, 07:49 PM
P: 43
So my freq = 5000Hz
and my Amplitude = 50V.
willib
#11
Jun22-05, 08:09 PM
P: 228
as LeBrad and Delta said in your equation [tex]Vs = A*sin({\omega}t })[/tex] A=50 and [tex]\omega[/tex]= 5000 ..
Maybe you are confused between Evaluating the equation and identifying the parameters ..
to evaluate the equation ,plug in T=0 or any value for t
So my freq = 5000Hz
no [tex]\omega[/tex]= 2Pi f
so your frequency in Hz 5000/2Pi
celect
#12
Jun22-05, 08:42 PM
P: 43
So are you stating I should have as an answer 5000/2 pi
the freq = 2500 pi Hz
willib
#13
Jun22-05, 08:50 PM
P: 228
Quote Quote by celect
So are you stating I should have as an answer 5000/2 pi
the freq = 2500 pi Hz
no i mean you should get 2500/pi Hz
approx 795 Hz..
celect
#14
Jun22-05, 08:56 PM
P: 43
Ok, I'm checking myself with text that has answers in back for just odd numbers.
the only answer they give is 2500/pi Hz
but the true answer is to go another step and divide the 2500 by pi.
ok
thanks.
123456
#15
Jul16-07, 07:54 AM
P: n/a
Sir

I want to know the frequency of the sound using the hexadecimal value of sound.can u please tell me the formula for that.
berkeman
#16
Jul16-07, 01:53 PM
Mentor
berkeman's Avatar
P: 40,730
Quote Quote by 123456 View Post
Sir

I want to know the frequency of the sound using the hexadecimal value of sound.can u please tell me the formula for that.
Why would you want to convert the decimal frequency of sound into a hex number? What is the context of your question? Do you maybe mean convert between Hz (cycles per second) and Radians per second?
xez
#17
Jul16-07, 02:22 PM
P: 175
Hexadecimal is just base-16 using digits
0123456789abcdef
corresponding to decimal values 0-16.
Use a conversion calculator to get the decimal value,
or calculate it digit by digit as the sum of h * 16^n where
h is your hex digit in that place, and n increases from 0
on the right up to however many total hex digits you have.

As to the frequency that corresponds, that cannot be said
using only the information you've provided since generally
a hexadecimal number will correspond to some divisor value relative to some reference clock frequency that is
specific to a given digital system...
berkeman
#18
Jul16-07, 02:25 PM
Mentor
berkeman's Avatar
P: 40,730
Quote Quote by xez View Post
Hexadecimal is just base-16 using digits
0123456789abcdef
corresponding to decimal values 0-16.
Small typo -- 0x0 to 0xF corresponds to decimal 0-15.


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