Posted: 7/25/2016 8:22:57 PM EDT
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Reverse rotation when thrown at the ground...
Example: grab a tennis ball the throw it to the ground with a considerable amount of backspin, when it contacts the rotation changes from backspin to front spin. |
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Quoted:
When it spins one way, it exerts a force in that direction. The ground reacts with equal and opposite force. The ball having much less mass than the planet, will have its direction reversed. Just my  SWAG. Never really gave it much thought.
This is an assumption. OP never specified the mass of the ball. edit: yes I know he did use a tennis ball as an example but never stated an absolute rule for the equation. |
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Quoted:
When it spins one way, it exerts a force in that direction. The ground reacts with equal and opposite force. The ball having much less mass than the planet, will have its direction reversed. Just my SWAG. Never really gave it much thought.
You are, in fact, correct. The unmoving ground resists both the vertical and rotational vectors that were imparted on the ball when it was thrown, and upon rebounding, imparts a vector directionally counter to both original vectors...............(wait for it....shameless Gary Larsen ripoff......... "then a miracle happens"...............( hey! at least I gave him credit  ) ..........and the ball changes direction in both vectors.
Dammit I do love me some science 
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