Physics: transverse wave & wavelength & motion

[YMMMA]

Homework Statement

the question asks at which point is the string moving upward at the instant shown?

Homework Equations

No equations needed

The Attempt at a Solution

I am not sure how I should approach this type of questions.
A) will move downward
B) downward then upward
C) upward then downward
D) same as C
E)upward then downward
Am I correct?

 

[YMMMA]

Here I think its clear that spoke P will move up, but Q will move up then down. Answer is A so Q will move down. Should I approach the question above the same as this one?

 

[Janosh89]

The upward direction is the direction of the y ^ arrow , -if you simply start at the left 0 and follow
the string with a pen top you will find there are TWO of the points from the A-B-C-D-E list of shown points
where where your pen top is traveling upward in the general direction of y ^.

 

[YMMMA]

The upward direction is the direction of the y ^ arrow , -if you simply start at the left 0 and follow
the string with a pen top you will find there are TWO of the points from the A-B-C-D-E list of shown points
where where your pen top is traveling upward in the general direction of y ^.

So, you’re saying it could be C and E,right?
I understand now that pointing away from the x-axis means upward and pointing toward the x-axis means downward,yes?

 

[Janosh89]

y^ is upward above 0 , y ∨ [downward arrow] below 0 is , of course, downward. By convention (Cartesian axes) y^ is usually
only given.
For representing waveforms / "string" , negative numbers of y ( ∨ or y below 0 ) are not that important -for SATS anyway-
The amplitude of the waveform ,or maximum distance from the horizontal x axis, can be taken at the turning point ("crest")
above the x-axis , namely point A. [ since below is a mirror image in the question]
Sorry, my bad, I overlooked D aswell. Your pen top will be traveling upward [ direction y^] at that point as well.
Please give the actual question at the start.

 

[YMMMA]

y^ is upward above 0 , y ∨ [downward arrow] below 0 is , of course, downward. By convention (Cartesian axes) y^ is usually
only given.
For representing waveforms / "string" , negative numbers of y ( ∨ or y below 0 ) are not that important -for SATS anyway-
The amplitude of the waveform ,or maximum distance from the horizontal x axis, can be taken at the turning point ("crest")
above the x-axis , namely point A. [ since below is a mirror image in the question]
Sorry, my bad, I overlooked D aswell. Your pen top will be traveling upward [ direction y^] at that point as well.
Please give the actual question at the start.

Here is it in full. I actually solved it as D before posting this. Can we say that points C and E are the nodes so at this instant they’re neither up or down?

 

[YMMMA]

Here I think its clear that spoke P will move up, but Q will move up then down. Answer is A so Q will move down. Should I approach the question above the same as this one?

Here’s an explanation for this one. But still I am confused.

 

[Janosh89]

Q6 one wavelength = two 'loops' . Answer?

 

[YMMMA]

Q6 one wavelength = two 'loops' . Answer?

Answer C

 

[Janosh89]

Correct. Question 7 isn't in the English language.
Q 8 Hint Forget about nodes. D is correct, but is your pen top going upward at any any other points aswell?

 

[YMMMA]

Correct. Question 7 isn't in the English language.
Q 8 Hint Forget about nodes. D is correct, but is your pen top going upward at any any other points aswell?

7 asks about twice the period, so E

Pen top points upward at 3 points as you said earlier..

What confuses me more is the other question, should approach post #1 the same way?

 

[Janosh89]

No, I think the graph (Side View) shows the x axis as velocity.. There is no origin 0 given and the other axis (y axis ) is
displacement. This is a traveling wave, so as the answer says- the next point p towards the origin 0 at extreme left,i.e the preceding dot
is
for point P - HIGHER than point P ∴ P will move upwards
for point Q - LOWER than point Q ∴ Q will move downwards

You could label the preceding ' dots' for P as P_o
...........for Q as Q_o ____ so P is P₁ and Q is Q₁

 

[YMMMA]

No, I think the graph (Side View) shows the x axis as velocity.. There is no origin 0 given and the other axis (y axis ) is
displacement. This is a traveling wave, so as the answer says- the next point p towards the origin 0 at extreme left,i.e the preceding dot
is
for point P - HIGHER than point P ∴ P will move upwards
for point Q - LOWER than point Q ∴ Q will move downwards

You could label the preceding ' dots' for P as P_o
...........for Q as Q_o ____ so P is P₁ and Q is Q₁

Got it, thanks!
But this question is different from the other?

 

[YMMMA]

If it’s the same question would be followed reasoning be correct? >>> Like point Aο lower that A so downward, same goes with all. Except in B will move upward?

 

[Janosh89]

Ahh... I took your first post #1 too literally . The x-axis here is distance (horizontal). The question would / should have said
when is the transverse wave/string moving upward . Since its motion is perpendicular to the x-axis, the only possible answer
is A.
In the second part /second question - which you understand - the x-axis is velocity , so your reasoning in #14 would be incorrect.

 

[YMMMA]

Ahh... I took your first post #1 too literally . The x-axis here is distance (horizontal). The question would / should have said
when is the transverse wave/string moving upward . Since its motion is perpendicular to the x-axis, the only possible answer
is A.
In the second part /second question - which you understand - the x-axis is velocity , so your reasoning in #14 would be incorrect.

Understood, Thank you!