A woman stands on a bathroom scale in a motionless elevator. When the elevator begins to move, the scale briefly reads only 0.90 of her regular weight.

1 m/s² down

Explanation:

"Calculate the acceleration of the elevator, and find the direction of acceleration."

Sum of forces in the +y direction:

∑F = ma

N − mg = ma

0.9 mg − mg = ma

-0.1 mg = ma

a = -0.1 g

a = -1 m/s²

it takes about 30 days for it to break down

2b2t

explanation:

2b2t