Final answer:
The mass of turmeric should be greater than 1 unit to ensure that any change in weight is detectable, as smaller proportions of change are harder to detect according to the Weber-Fechner Law.
Step-by-step explanation:
The mass of turmeric should be greater than 1 unit because the detectability of a weight difference depends on the proportion of the change, rather than the absolute value. A difference between 1 and 2 units of weight represents a 100% increase, which is more likely to be detectable than a difference between 2 and 4 units, which is only a 100% increase as well. This is an application of the Weber-Fechner Law in psychology, which suggests that the noticed difference between two stimuli is proportional to the magnitude of the stimuli.