Why Is the Lag Time 60 Degrees Instead of 72 Degrees in Wave Phase Calculations?

[ishterz]

Hi,

I came across this question on waves which tells you how to calculate the phase difference and the lag time but I don' uderstand why it is 60 degrees.Although I'm notable to draw th diagram,I will write down the explination

What is the phase relationship b/w the two signals?(y1 and y2)

The difference between the squares of the signals on the graphs is 4 and one wavelenght of y2 is 20 squares.
So it says that the lag is 1/5 of a cycle of 360 degrees which is 60 degrees.

I understand where the 1/5th came from but how is it 60 and not 72 which is what you get after you divide 5 by 360? I thought the answer was wrong but similar questions have answers mismatched with mine as well.

So please help! I've got my exam tomorrow!

Thanks

 

[cartonn30gel]

According to your description, I can't find any flaws in your solution. Especially if it says "the lag is 1/5 of a cycle of 360 degrees which is 60 degrees", there is probably a small math error. I can't be sure without the diagram though.

Can you try to post a picture?

 

[ishterz]

I tried posting the picture up but it was unsuccessful. I've pretty much described it in the question though.
I don't understand,how is 60 1/5 of 360? isn't it 1/6th ? Why is it saying 1/5th ? =S

 

[cartonn30gel]

They probably just made a small mistake. Try some other examples and the concepts will become clearer. Don't get hung up on the same problem.

 

[rdl]

for your question! Phase difference and lag time are important concepts in the study of waves, and understanding them is crucial in many fields of science, including physics, engineering, and astronomy.

To begin with, let's define what we mean by phase difference and lag time. Phase difference refers to the difference in the starting point of two waveforms. It is usually measured in degrees or radians and can be positive or negative. On the other hand, lag time refers to the delay between the two signals reaching their maximum or minimum values. It is usually measured in seconds or fractions of a cycle.

Now, going back to your question, it seems like you are trying to calculate the phase difference and lag time between two signals, y1 and y2. The given information states that the difference between the squares of the signals is 4, and one wavelength of y2 is equal to 20 squares. From this, we can determine that the amplitude of y2 is 2 squares (since 20 divided by 4 is 5, and the amplitude is half of the wavelength).

To calculate the phase difference, we need to find the difference in starting points of the two signals. Since we know the amplitude of y2 is 2 squares, we can assume that the starting point of y2 is at the peak of the wave, which is 90 degrees. On the other hand, the starting point of y1 is not given, but we can assume it is at the zero point (0 degrees). Therefore, the phase difference between the two signals is 90 degrees.

As for the lag time, we need to find the delay between the two signals reaching their maximum values. Since we know the amplitude of y2 is 2 squares, we can assume that it reaches its maximum value at 90 degrees. On the other hand, y1 reaches its maximum value at 0 degrees. Therefore, the lag time between the two signals is 90 degrees, which is equivalent to 1/5 of a cycle (360 divided by 5). This is why the lag time is 60 degrees, not 72 degrees, as you initially thought.

I hope this explanation helps in understanding the concept of phase difference and lag time. Remember, it is important to carefully analyze the given information and assumptions when solving problems involving waves. Good luck on your exam!