Final answer:
If the Elevator shaft ventilation is to be used for ventilation, the elevator must be moving upward with a constant velocity, creating airflow in the shaft. This allows fresh air to enter the lower levels while pushing air upward in the shaft.
Step-by-step explanation:
If the elevator shaft is to be used for ventilation, the elevator must be moving upward with a constant velocity. This is because the movement of the elevator creates airflow in the shaft, which helps in circulating air throughout the building.
When the elevator moves upward with a constant velocity, air from lower levels is pushed upward, allowing fresh air to enter the lower levels.
For example, if the elevator is moving upward at a constant velocity of 2 meters per second, it creates a positive pressure at its base, pushing air upward in the shaft.
Meanwhile, fresh air enters the lower levels to replace the air that is being pushed upward. Therefore, to use the elevator shaft for ventilation, it is important to ensure that the elevator is moving upward with a constant velocity.