What is the etiquette of having a trolley in the form room
Translation and rotation are for rigid bodies, so the distance between the object at any point in motion is constant, and it doesn't become its mirror image. The motion of a point can always be seen as translational. Translation is the motion of an object, moving from one point to another, from one point to the other. It can also be defined as the movement of "the same movement" on every point in the object when it moves. One definition is not so good, after the initial position is not the same as "sports is the same, but the trajectory shape is the same size, but not necessarily" movement is the same, such as a circular ring around the heart, each point of trajectory is same shape and size is the same. Rotation is when an object moves, each point from the same point (can) outside the object distance constant movement, known as turn around this point, the point is called the center of rotation of the object.
So, it doesn't have to be around some axis. I remember my high school book has "do translation and rotation", to clarify, "both for translation and rotation," usually "is not translation", not to turn, only can be seen as a sum of two kinds of sports. When I say "usually", it means that the rotation around a certain point can be regarded as the rotation of another point plus a translational result! Especially in the center of rotation outside objects, often also be regarded as "both for translation and rotation," by this time the movement "is turning, but it is not translation". Also, there is a common case of moving objects around a center of mass (or geometric center)
That is often take in the center of the rotation center of mass, or the form of geometric center, the center of mass (or geometric center) if there is movement is called a "translation", regardless of whether can be seen as an object around another little exercise. This is especially important due to the low level of people in high school.