One of the qualities of measuring instruments is speed. A measuring instrument is  quick if it needs little time to callibrate before beginning the measurement and if the needle or cursor quickly comes to rest by a value on the scale when we carry out the measurement.
As you can observe, the bathroom scales in the following visual do not produce the measurement instantaneously, when we stand on it or when we get off it.

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Ministerio de Educación, Cultura y Deporte