During holidays，Kitty usually goes to see the exhibits in many museums，such as the history museum，the art museum，the museum of science and technology and the museum of natural history．There are thousands of wonderful things in museum.There are paintings，sculptures(雕塑)，costumes(服饰)，swords(剑)，ancient animal bones and plants，stuffed animals(动物标本)and many others．It is always a good review of history to visit those museums．It is also a great way to learn more things by myself．

若关于x的方程$\left|x+\frac{1}{x}\right|-\left|x-\frac{1}{x}\right|-kx-1=0$有五个互不相等的实根，则k的取值范围是（）

下列物理量中，属于矢量的是（　　）