# Radius of circular impulse wave in the hemisphere bowl

1. Jul 7, 2014

### desmond iking

1. The problem statement, all variables and given/known data

hi all, why the wave is reflected back form the centre when it is at the distance of 200mm? why the wave cant go beyond 200mm to reach 250mm from the side of bowl?

2. Relevant equations

3. The attempt at a solution

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2. Jul 7, 2014

### TSny

Can you describe the shape of the wavefront just after tapping the side of the bowl? I'm not sure, but you might have a misconception about this. If in doubt, try it in the kitchen

What does the wavefront in the problem look like at t = 0.8 s?

3. Jul 8, 2014

### desmond iking

the wavefront move until the another end from one end and reflect back.

4. Jul 8, 2014

### Nathanael

So you're saying it would be like a line moving across the bowl and then back?

5. Jul 8, 2014

### desmond iking

Yes. Is it wrong?

6. Jul 8, 2014

### Staff: Mentor

It does seem wrong to use the word "reflect" to describe the wave progressing through the centre of the bowl. There is no discontinuity in the medium there for a wave to "reflect" off.

There is no phase inversion, yet they imply it can be viewed as 100% "reflection"?

7. Jul 8, 2014

### TSny

Did you do the experiment?

Here is what I observed. Picture A shows the water sitting still in the bowl before tapping the bowl.

B, C, and D show times just after tapping the bowl on the left with the handle of a knife.

#### Attached Files:

• ###### Waves in Bowl.jpg
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8. Jul 10, 2014

### desmond iking

sorry i cant understand your photo here. can i still say that the water the wavefront move until the another end from one end and reflect back. which means the water wave can move until 400mm from one end and then only reflect back? which is also (assuming the water wave is produced at the left ) means the water wave is at 150 mm form the right...

9. Jul 10, 2014

### Nathanael

As you can see from TSny's pictures, that is not what happens. (It is not a line; what shape is it?)

10. Jul 11, 2014

### desmond iking

11. Jul 11, 2014

### Staff: Mentor

Perhaps you could write a few sentences in response to those trying to help you? By confining yourself to a single staccato phrase, you have misled some into thinking you can't conceive of circular wave propagation. Well. I think you have managed it, anyway ...

Maybe I'm the one who's got it wrong. You have tried tapping on the side of a bowl of water?

Last edited: Jul 11, 2014