If any forces that are external to the cannon-&amp;-ball system (such as weight and friction) are removed.
(any forces; are; external to the cannon-&amp;-ball system (such as weight and friction) (any forces that are external to the cannon-&amp;-ball system (such as weight and friction); are removed; )
any forces any forces that are external to the cannon-&amp;-ball system (such as weight and friction)
are are removed
external to the cannon-&amp;-ball system (such as weight and friction