[_sparks]

Question:


Answer:



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?
Please answer.
Thanks

[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?

[_sparks]

(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?

[Pangol]

(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.