# Doc talk:Ball Bounce

Although I am still a newbie on Synfig, I have tried to achieve the math-related solution, it may be the simpler aswell!

I am not sure to have understood all the concepts used, that's why I guess it is not completely correct.

My approach is to imagine x and y movements as independent, so the x is simple (uniform rectilinear movement) and the y a little more complex. The first idea was to use the classical equations for acceleration (and gravity), but this would lead to need one equation per step (up-down or down-up). The ultimate idea is to use the sine function to describe the position at each timepoint, so... one equation would last forever!

Steps:

• Origin converted to compound
• X manualy animated to go linearly from left to right of the canvas: simple.
• Y converted to sine
• Sine Amplitude set to 1 (why? I tried to set this to -172, wich is the initial height of the circle but it disappeard! Well, just works)
• Sine DEG to time loop, and then:
• Timeloop link to 0 at 0 seconds and 180 at 1 second
• Timeloop duration: 1 second
• Rest timeloop parameters left to 0

I guess the result is almost correct although the shape of the curve is not perfect, but I don't know why. I don't know how to upload a screenshot. Any help? Can you correct this?