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# Water Waves Question Watch

1. Question:

Hi,
I don’t understand question 12b and 12c.
Isn’t the arrow supposed to be pointing upwards at point Y?
And why does B have to be at a point of maximum displacement(antinode), isn’t it supposed to be in the equilibrium line?
Thanks
2. The wave is moving to the right. That means that the portion on the right of the point Y has already passed Y. So just before this picture was taken, the point Y was higher up, and in a few moments, it will be lower down. Therefore, the water at point Y is moving downwards.

As for the second part, think what would happen if you were neck-deep in the water, being lifted up and moved down in time with the waves. When would you be motionless?
3. (Original post by Pangol)
The wave is moving to the right. That means that the portion on the right of the point Y has already passed Y. So just before this picture was taken, the point Y was higher up, and in a few moments, it will be lower down. Therefore, the water at point Y is moving downwards.

As for the second part, think what would happen if you were neck-deep in the water, being lifted up and moved down in time with the waves. When would you be motionless?
Oh okay thanks now i understand
And it is at rest at maximum displacement as it is about to change direction. Just like a projectile right?
4. (Original post by _sparks)
And it is at rest at maximum displacement as it is about to change direction. Just like a projectile right?
Yep. Although be careful with a projectile. If it is thrown straight up, it is at rest at its greatest vertical height. If it is moving in a projectile way, it has its minimum speed at its greatest height, but not zero speed.

Updated: May 17, 2012
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