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# 2 very basic edexcel AS wave questions i dont understand :O watch

1. 1) In a ripple tank, two dippers D1 and D2, 6cm apart, produce coherent waves of wavelength 4cm. Is point X a maximum or minimum?
where is point X? how do I find out whether its a maximum or minimum?

2)Waves are sent along a spring with a velocity of 0.25ms^-1. The wave is travelling to the right, with wavelength 0.50m and frequency 0.5Hz.

On a displacement-distance graph, point X is at (0,0) and point Y is at (0,-30). Sketch the graphs of displacement against time for points X and Y
i have no idea where to begin. i don't even understand the question , can somebody break it down for me please? would be much appreciated

THANK YOU !!
2. (Original post by dumb maths student)
1) In a ripple tank, two dippers D1 and D2, 6cm apart, produce coherent waves of wavelength 4cm. Is point X a maximum or minimum?
where is point X? how do I find out whether its a maximum or minimum?

2)Waves are sent along a spring with a velocity of 0.25ms^-1. The wave is travelling to the right, with wavelength 0.50m and frequency 0.5Hz.

On a displacement-distance graph, point X is at (0,0) and point Y is at (0,-30). Sketch the graphs of displacement against time for points X and Y
i have no idea where to begin. i don't even understand the question , can somebody break it down for me please? would be much appreciated

THANK YOU !!
1) You're probably missing some sort of diagram!
3. 1) I agree with unamed; there is a missing diagram showing where X is.
2) I find this part a bit vague too. It looks like it's asking you to say how a point on the spring, at the origin (0,0 the start of the spring, I assume) is going up and down as the wave passes. You plot this over time. The horizontal axis is time and the vertical is displacement. You know that the wave will perform one complete cycle on the time axis in 2 seconds. (Its frequency is 0.5 Hz, period is 1/f)
On the other hand, without being given the amplitude of this wave in the question, you will just have to make this up. Call it "A", the amplitude of the wave on the graph.
4. 1) Yep, diagram probably missing. HOWEVER, when you see where point X is, if the path difference between D1 and D2 is 0 OR a whole number of wave lengths apart, then it is a position of maximum amplitude i.e. it is at an antinode. However, if the point has a path difference of half wavelengths, or Pi Rads apart, then destructive interference occurs, and the amplitude will be zero.

2) Yep, pretty much what Stone bridge has said. It's basically a sine graph.

hope that helps

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