# Wave equation diagram problem

• JI567
In summary, the conversation was about a question asking for sketches for different values of t in the wave equation Ytt = Yxx with given initial conditions. The sketches were provided and confirmed to be correct by an expert. The asker's reason for seeking confirmation was to ensure they receive full marks on their work.

## Homework Statement

The question is to sketch for values of t = 0, t =0.25, t = 0.5, t=1 and t = 1.25 for the wave equation

Ytt = Yxx in the infinite domain with initial conditions

y(x,0) = f(x) =
\begin{cases}
1 & \text{if } 0 ≤ x ≤ 1 \\
& 0 (otherwise)
\end{cases}

Yt(x,0) = 0

## Homework Equations

Y(x,t) = a(x,t) + b(x,t)

where a(x,t) = ## \frac {1} {2} \ ## f(x+t)
and b(x,t) = ## \frac {1} {2} \ ## f(x-t)

## The Attempt at a Solution

These are the sketches I obtained for those times and they are not to exactly measured to the points as I did them in paint. Can someone please tell me if the sketches are correct for this question!

for t =0

for t= 0.25

Attaching the remaining ones in the post below as you can't attach more than 6 in one post.

#### Attachments

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for t = 0.5 s

for t = 1 s

Hi JI,

As you may know, PF has great difficulty handing out approval stamps: it could create big problems with teachers, exam committees and what have you. PF homework is meant to help folks when they get stuck; with hints, questions and advice. My personal opinion is you don't need any of those :)

and ;)

BvU said:
Hi JI,

As you may know, PF has great difficulty handing out approval stamps: it could create big problems with teachers, exam committees and what have you. PF homework is meant to help folks when they get stuck; with hints, questions and advice. My personal opinion is you don't need any of those :)

and ;)

Look man can you be more clear? I don't understand what are you talking about. All I asked is if my sketches are correct or not, I am not asking you to do my homework for me.

Yes I can be more clear: I think what you did is excellent -- but you can't derive any rights from my statements.

My post #3 tries to express some reluctance about the "Is this correct" questions.

BvU said:
Yes I can be more clear: I think what you did is excellent -- but you can't derive any rights from my statements.

My post #3 tries to express some reluctance about the "Is this correct" questions.

Cheers mate! I just realized I missed out t= 1.25 s for this question

Can you see the sketches for t = 1.25 s are excellent as well

As I said: you're so good you don't need assistance here :)

You do have me wondering what's the reason you ask for confirmation: you clearly understand everything that's going on, so why this possible doubt ?

BvU said:
As I said: you're so good you don't need assistance here :)

You do have me wondering what's the reason you ask for confirmation: you clearly understand everything that's going on, so why this possible doubt ?

Cheers! I just want to be 100% sure that my works are correct so that I get full marks...so even if I understand everything I want to confirm with people who has more knowledge than me.