When taking the elevator, experience your own movement and quietness, and talk about what the reference object is.

When you take the elevator, feel your own movement and stillness.

Taking the elevator as a reference object, the position of people and the elevator is unchanged and static relative to the elevator.

Taking the ground as a reference, the position of people and the ground is changing and moving relative to the ground. reference substance

In the study of mechanical motion, people take the pre-selected and assumed immobile objects as benchmarks, which are called reference objects. (generally don't take the research object as a reference)

1, objectivity-everything in the universe is in endless motion, and there is no absolutely static object. Usually, when we say that an object is moving or stationary, it is relative to another object (reference). When describing the movement of an object, reference always exists whether it is mentioned or not, which is the objectivity of reference.

2. Assumption-the reference object is only assumed to be motionless, not really motionless. Like other objects, it is in perpetual motion. This is the assumption of the reference object. Some students think that reference objects are immovable objects. This understanding is completely wrong.

3, multiplicity-because to judge whether an object is moving or static, the key is to see what object to choose as a reference. Therefore, the motion we study is relative motion, which is the multiplicity of reference objects, that is, the study of the same object. Different reference objects can be selected. When different reference objects are selected, the results describing the motion of objects are often different. For example, passengers sitting on a bus at a constant speed are stationary if they take the car as a reference; If the roadside trees are taken as reference objects, they are moving.