physics

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A 640 N student stands on a bathroom scale in an elebator. As the elevator starts moving, the scale reads 800 N. a) find the acceleration of the elevator (magnitude and direction) b) acceleration if the scale reads 450N? c) If the scale reads 0 should the student worry? Explain.

a) was 2.45m/s^3 up
b) -2.91m/s^2
c) free fall, and worry but I don't understand why.
What were the equations used?


apparent weight = mass*g + mass*acceleration.

When it goes up, apparent weight is greater, when it goes down, apparent weight is smaller, in free fall, a= g, so
apparent wegith= mg-mg=0

In the free fall, what forces are acting on the scale and the student? Answer, exactly the same force (gravity) is accelerating both at the same rate, there is no apparent difference in acclerations (forces) between them.

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