My friend Tony is an American1 . He is ten years old. He lives2his family in China now. There are3 people in his family; his mother Mrs. Green, his father Mr. Green and his little sister Amy. He has a white cat.4name is Betty. Look！Amy is playing5 Betty. His father, Mr. Green, is watc­hing TV. His mother is doing housework. What about Tony? He is doing6Chinese homework. He can't  7Chinese well, but he likes Chinese very much. Tony's8works in a TV station. His father works in a school as an9 teacher. Tony and his sister  10 to the same school.

设$x\in R$,向量$\overrightarrow{a}=\left(2,x\right)$,$\overrightarrow{b}$=(3,—2),且$\overrightarrow{a}\perp \overrightarrow{b}$则$|\overrightarrow{a}-\overrightarrow{b}|$=（　　）