# Determining a specific frequency to make the ball bounce

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1. Jan 22, 2015

### chemaie

So, here's the set-up:

A small stereo speaker is connected to a function generator. A concave lens, bearing a ball is place over the speaker.

Now, the frequency is slowly increased in the function generator. My question is,
Will the ball really bounce at a certain frequency? Because I am not really sure about it. I just a found that set-up from a problem in a book and I want to try it for my research. And also, if it will bounce, what causes it to bounce? Is it the vibration of the lens?

2. Jan 23, 2015

### RUber

I have seen plenty of things bounce when affected by sound, so I think it must be true.
First, try to characterize the force acting on the ball. I would think that it must be the vibration of the lens, so force would be a function of frequency.
Next you would need to define the time it takes that ball to return to the lens. If the phase of the vibration is off, you will not get the constructive effects needed to keep the ball bouncing.
I would imagine you would need to consider both power and frequency, since the timing of the bounce would depend on both factors.

3. Jan 26, 2015

### chemaie

Thank you for your response, RUber. I will try to consider the factors affecting the ball to bounce. Also, I would like to know the relationship of the frequency to the acceleration of the ball. Is there any relationship between the two?