It means that it is going up, but slowing down. Like it is going up from the lobby and about to stop at some upper floorjwviviang said:TL;DR Summary: I just have a question (I don't know how to word this summary, sorry)
If an elevator is moving upward, what does a downward acceleration mean?
In principle you can have up be either positive or negative, whatever you prefer. However, I personally think that having up be negative is confusing, so I would recommend usually choosing up positive.jwviviang said:When applying the free body diagram, will the positive direction be upwards since the elevator is moving up?
If acceleration has a component opposite to velocity, then the object is slowing down.jwviviang said:If an elevator is moving upward, what does a downward acceleration mean?
You are free to choose the orientation of your coordinate system axes, as long you apply that convention consistently.jwviviang said:When applying the free body diagram, will the positive direction be upwards since the elevator is moving up?
A.T. said:If acceleration has a component opposite to velocity, then the object is slowing down.You are free to choose the orientation of your coordinate system axes, as long you apply that convention consistently.
I see now. So if a question says (for example) "...moving upward elevator...if the elevator has a downward acceleration a = 1.4 m/s^2..." the downward acceleration means a = -1.4 m/s^2?Dale said:It means that it is going up, but slowing down. Like it is going up from the lobby and about to stop at some upper floor
In principle you can have up be either positive or negative, whatever you prefer. However, I personally think that having up be negative is confusing, so I would recommend usually choosing up positive.
So your acceleration would be negative and your velocity would be positive.
Yes, in the usual setup with up being positive.jwviviang said:I see now. So if a question says (for example) "...moving upward elevator...if the elevator has a downward acceleration a = 1.4 m/s^2..." the downward acceleration means a = -1.4 m/s^2?
When an elevator has a downward acceleration, it means that the elevator is either speeding up as it moves downward or slowing down as it moves upward. In physics, acceleration is a vector quantity that indicates the rate of change of velocity. A downward acceleration specifically indicates that the velocity of the elevator is changing in the downward direction.
You can feel the effects of downward acceleration in an elevator through changes in the apparent weight you experience. If the elevator is accelerating downward, you may feel lighter because the normal force exerted by the floor of the elevator on you decreases. Conversely, if the elevator is decelerating while moving upward, you may feel heavier temporarily.
When an elevator experiences downward acceleration, the primary forces acting on it are gravity and the tension in the elevator cable. Gravity pulls the elevator downward, while the tension in the cable works against this motion. If the elevator is accelerating downward, it means the net force is in the downward direction, indicating that the force of gravity is greater than the tension in the cable.
Downward acceleration in itself is not necessarily dangerous as long as it is within safe limits. Elevators are designed with safety mechanisms to ensure that acceleration and deceleration are controlled and gradual. However, if an elevator were to experience uncontrolled or excessive downward acceleration, it could potentially be dangerous, which is why elevators are equipped with emergency brakes and other safety systems.
Engineers control the acceleration of elevators using sophisticated control systems that manage the motor and braking mechanisms. These systems ensure smooth and gradual changes in velocity to provide a comfortable ride for passengers. Sensors and feedback loops continuously monitor the elevator's position, speed, and acceleration, allowing the control system to make real-time adjustments to maintain safety and comfort.