142682
At time t = 0 the wall is made to move with constant speed U in a fixed direction ( for definiteness , say the x direction and consider only the x-y plane ) .
 None
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
 Entities:  
Answer:
 None