An object is placed on a scale under what conditions does the scale read something other than the objects weight even though the scale is functioning properly and is calibrated correctly?

Answer 1

-- The scale itself is accelerating vertically, either upward or downward.

-- The scale and object are falling.

-- The scale and object are in an elevator which is either just starting out or just coming to rest.

-- The scale and object are on a space vehicle during or after launch, or in transit, or during re-entry or landing.

-- The scale and object are on the moon, or on another planet. In either of these cases, the scale reads
the correct 'weight', but it's not the reading you expect, since it's not the object's earth weight.

Answer 2

The scale may read something other than the object's weight if the object is accelerating, such as during free fall. In this case, the scale would read zero, as both the object's weight and the scale's reading are due to gravitational acceleration. In other instances, if there is an additional force acting on the object, such as a strong upward or downward wind, it could affect the scale's reading.