A person stands on a bathroom scale in a motionless elevator. When the elevator begins to move, the scale brie

A person stands on a bathroom scale in a motionless elevator. When the elevator begins to move, the scale briefly reads only 0.78 of the person's regular weight. Calculate the acceleration of the elevator, and find the direction of acceleration.

i searched other ways to do this but all of them say mg in them...what do that mean?

i need to know what every letter means(:

The net acceleration is .78g = g - a; so the elevator acceleration is a = g - .78g = .22g where g = 9.81 m/s^2. Thus a = .22*9.81 = 2.16 m/s^2 downward (same direction as g). ANS.

Note we do not need the mass, m, at all. That results because mA = m.78g = mg - ma is the balance of forces, but all the m's cancel out, leaving only the accelerations. Note that W = mg is the person's weight on the scale when the elevator is not moving.