7820
This speed of sound for pressure waves in long rods will always be slightly less than the same speed in homogeneous 3-dimensional solids , and the ratio of the speeds in the two different types of objects depends on Poisson 's ratio for the material .
 person: Poisson
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 person: Poisson