# Angle of incidence and reflection

1. Feb 3, 2015

### Robben

I am trying to write a java code where the user inputs the height at which a solid body approaches a sphere of radius R and outputs the angle $\theta$ at which the body bounces off the sphere.

I have all my code written is just that I don't know how to derive the equation that calculates the angle $\theta$.

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Last edited: Feb 3, 2015
2. Feb 4, 2015

### lowerlowerhk

Break down the velocity vector of the solid body into two components: one is tangential to the sphere, another one points to the centre of the sphere. Reverse the direction of the central component and add the two component together and you will have the bounce off velocity vector. The angle between incident and reflected angle is what you need. Divide it by two and you will have the answer. Does it help?

3. Feb 4, 2015

4. Feb 4, 2015

5. Feb 4, 2015

### Robben

I got it to work now.

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Last edited: Feb 4, 2015
6. Feb 5, 2015

### dmpnow

can you post the code?