Hotel revolving door

First, the revolving door of the hotel rotates when working.

2. 1. Rotation phenomenon: the phenomenon of rotating around a fixed center point is called rotation phenomenon. When an object rotates, its direction will change, but its shape and size will not change.

2. Translation phenomenon: when an object is moving, it can be translated in any direction, and the direction remains unchanged after translation. The shape and size will not change.

3. 1. When the revolving door works, gravity and supporting force act in the vertical direction, with equal magnitude and opposite directions. The revolving door rotates around the axis after being stressed. Its top view is as follows:

The motion of the revolving door is close to circular motion, which shows that the centripetal force of the object is always perpendicular to the speed direction in circular motion. The direction of centripetal force (provided by the material tension of the door itself) points to the center of the circle along the radius and is always perpendicular to the speed direction. In any circular motion, the centripetal force must point to the center of the circle along the radius, and the speed is tangential, so the centripetal force must be perpendicular to the speed direction. Therefore, when the revolving door moves, the direction will change, and the shape and size will not change, which conforms to the definition of rotary motion.

2. Taking an object sliding on a slope as an example, its force is as follows:

Objects are affected by supporting force, gravity and moving friction. Its final stress direction is consistent with the movement direction. So the object slides down the slope, which belongs to translational motion.