# Homework Help: Snapshot of a travelling harmonic wave

1. Nov 26, 2014

### PhysicsMan999

1. The problem statement, all variables and given/known data
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The graph shows a snapshot of a travelling harmonic wave; eight points are indicated. Answer the five questions by selecting from the choices below.

1. A) → B) ← C) ↓ D) ↑ E) the velocity is zero
1. If the wave is moving to the right, what is the direction of the velocity of the particle at point 6?
2. If the wave is moving to the left, what is the direction of the velocity of the particle at point 3?
3. If the velocity of the particle at point 3 is given by the arrow D, in which direction is the wave moving?
4. If the velocity of the particle at point 3 is given by the arrow C, in which direction is the wave moving?
5. If the wave is moving in the direction A, what is the direction of the velocity of the particle at point 7?
2. Relevant equations
None.

3. The attempt at a solution
I thought 1. up
2. down
3.right
4. left
5. up
not really sure what I'm doing wrong or if I've just completely misunderstood how to determine particle movement..

2. Nov 26, 2014

### haruspex

3. Nov 26, 2014

### PhysicsMan999

The program will only say its correct if you have all answers correct. I've got the answer now, but I'm not really sure why the velocity would be 0 at 7..would it also be 0 at one of the maximums?

4. Nov 26, 2014

### Miles Whitmore

Yes, the instantaneous velocity would be zero at either a maximum or minimum. Think of it like this: just before the minimum passes point 7, the point is moving down. After the minimum has passed the point, it would be moving up. So what happens in between those cases at the exact moment the point is at the minimum?

5. Nov 26, 2014

### PhysicsMan999

Ahh okay I get it now. Thanks guys!