What is the x>0 mean here? standing wave equation find nodes?

In summary: Thank youWhy I can't use dy/dT=0? Is that because x<0? What does that mean ? please . Thank youIn summary, the question is asking for the positions of the first two nodes with x>0 in a standing wave formed by two waves traveling in opposite directions with a formula of y= 2sin(31.42x)cos(7854t). The concept of nodes and antinodes is explained and it is suggested to use calculus to find the maxima. The question does not specify the starting point or length of x, making it difficult to calculate.
  • #1
Outrageous
374
0

Homework Statement


Two waves travel in opposite direction form a standing wave of y= 2sin(31.42x)cos(7854t).
Find the positions of first two nodes with x>0.


Homework Equations





The Attempt at a Solution


The question didn't say whether the standing wave starts from node or antinode . The question didn't say how long is x, even I know the wavelength and frequency also don't know how to calculate, how? Please help
 
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  • #2
Outrageous said:

Homework Statement


Two waves travel in opposite direction form a standing wave of y= 2sin(31.42x)cos(7854t).
Find the positions of first two nodes with x>0.


Homework Equations





The Attempt at a Solution


The question didn't say whether the standing wave starts from node or antinode . The question didn't say how long is x, even I know the wavelength and frequency also don't know how to calculate, how? Please help

Tell me what 'node' means.
 
  • #3
Dick said:
Tell me what 'node' means.

The point that is not moving in standing wave. X=0. Then t= 0 ,then I will get first node, the second node, t=2?

Thanks
 
  • #4
Outrageous said:
The point that is not moving in standing wave. X=0. Then t= 0 ,then I will get first node, the second node, t=2?

Thanks

No, a node is a point where y=0 for all values of t. Try to find the first two value of x that satisfy 2sin(31.42x)=0.
 
  • #5
Yup, y=0, thank you very much
 
  • #6
Then for antinode position is dy/dT= 0 ? The amplitude is maximum for all kind of y.
 
  • #7
The position of the first two antinode s with x< 0. X<0 here mean they want the x value be negative , if I use, dy/dt = 0, then I will get sin34.42x= 0 , how to make x become less than zero here? Please thanks
 
  • #8
Outrageous said:
The position of the first two antinode s with x< 0. X<0 here mean they want the x value be negative , if I use, dy/dt = 0, then I will get sin34.42x= 0 , how to make x become less than zero here? Please thanks

Antinode is where the amplitude reaches a maximum as a function of x. To find maxima you want to use calculus and solve dy/dx=0.
 
  • #9
Why I can't use dy/dT=0? Is that because x<0? What does that mean ? please .
 

1. What is the x>0 mean in the standing wave equation?

The x>0 in the standing wave equation refers to the position along the wave where the amplitude is measured. This means that only the points on the positive side of the x-axis are considered in the equation.

2. How is the standing wave equation derived?

The standing wave equation is derived from the general wave equation, which describes the behavior of waves in a medium. The standing wave equation is a special case of this equation, where the wave is confined within a specific space and does not travel.

3. What do the nodes represent in the standing wave equation?

The nodes in the standing wave equation represent points along the wave where the amplitude is zero. These points occur at regular intervals and are important for understanding the behavior and properties of standing waves.

4. How does the number of nodes affect the frequency of a standing wave?

The number of nodes in a standing wave is directly related to its frequency. As the number of nodes increases, the frequency of the wave also increases. This means that waves with more nodes have a higher pitch and shorter wavelength.

5. Why is it important to consider x>0 in the standing wave equation?

The restriction of x>0 in the standing wave equation is important because it allows us to accurately describe the behavior of standing waves in a specific space. Without this restriction, the equation would not accurately represent the behavior of standing waves and could lead to incorrect conclusions.

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