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This sand drawing illustrates a fable in which a rabbit , positioned at point B , discovers a salt mine ( point A ) . He broke into a wide smile and then a chuckle as audience members laughed . " Two parameters determine when this happens and ultimately what the image looks like : the distance advanced by each creature at each iteration of the process . People with increasingly frequent attacks of the episodic form may be at higher risk of developing the chronic form of the headache over a period of years . Newton 's laws provide a precise answer to the problem of determining the motion of two bodies under the influence of gravity .