AH"Calculate Acceleration & Direction of Elevator with Scale Help | SARAH

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In a motionless elevator, a person experiences a weight reading on a scale, which changes when the elevator begins to move. When the scale reads 0.72 of the person's regular weight, it indicates that the elevator is accelerating downward. To calculate the acceleration, one must consider the forces acting on the person: the gravitational force and the upward force from the scale. The net force is the difference between these two forces, which relates to the person's acceleration through Newton's second law, F=ma. By analyzing these forces, one can determine both the acceleration and its downward direction.
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A person stands on a bathroom scale in a motionless elevator. When the elevator begins to move, the scale briefly reads only 0.72 of the person's regular weight. Calculate the acceleration of the elevator, and find the direction of acceleration.
I know that the direction of acceleration is downward, but I'm not quite sure how to calculate it. I know that F=ma...
It would be much appreciated if someone could point me in the right direction.
Thanks
-SAR
 
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no, F is not equal to ma ... the SUM of all Forces is equal to ma .

The Earth pulls down on the person, and the scale surface pushes up on them.
 
The scale reads the force exerted on it, which is equal to the upwards force it exerts on the person standing on it. That person has two forces on them: the force of the scale pushing upwards, and the force of gravity pulling downwards. The net force on the person is the vector sum of these two forces.

So, here are the questions:

1. What is the force of gravity on the person?
2. What is the force provided by the scale?
3. What is the net force on the person?
4. How is the net force related to the person's acceleration?
5. What is the person's acceleration?
 

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