rod在物理中的意义an object with one dimension small in comparison w

rod在物理中的意义
an object with one dimension small in comparison with another(such as a metre or a beam) can be modelled as rod. This means that the mass of the object can be considerdto be distributed along a straight line,A rod has no thickness(it is one-dimensional) and is rigid(it does not bend or buckle)
上面是解释,rod是“刚体”吗?能否大概解释一下这段话的意思~谢啦~