Answer:
Air conditioning units are often placed close to the ceiling because of convection.
Step-by-step explanation:
Warm air tends to rise, so by positioning the AC unit near the ceiling, it can efficiently cool the warmer air at the top of the room. As the cold air is blown into the room, it displaces the warm air, creating a convection current that helps distribute cooler air throughout the space more effectively. This design maximizes the cooling efficiency and ensures a more even temperature distribution in the room.