Generate an overlapping word between the given two sentences. When you find the overlapping words, they don't have to match exactly, e.g., "survival" and "survive" are valid overlapping words. Little words like "the" or "of" don't count! You must generate significant words which are not the stop words.

[Q]: Sentence1: the mass of an object causes the gravitational force exerted by that object. 
Sentence2: gravitational force accelerates objects.
[A]: force


[Q]: Sentence1: Insects have 2 antennae. 
Sentence2: Insects have 2 appendages to detect sound.
[A]: 2


[Q]: Sentence1: water causes refraction of light. 
Sentence2: Rainbows are formed when light passes through water.
[A]:
light