Final answer:
Changes in size can refer to the concept of length contraction in physics as well as growth in biological systems. Proper length is an object's length in its own rest frame, while length contraction occurs at high speeds relative to the observer, unrelated to biological growth. In contrast, growth in weight and length in biology reflects health and development, as seen in babies and adolescents.
Step-by-step explanation:
Understanding Changes in Size
Changes in size, specifically weight and length, can be discussed within different contexts. In physical terms, such as in physics, we explore concepts like proper length and length contraction. However, in biological terms, growth in weight and length refer to physical changes in living organisms over time.
Proper Length and Length Contraction
Proper length is the measurement of an object's length within its rest frame. To calculate length contraction, used in the theory of relativity, one would need to apply the length contraction formula considering the object's velocity relative to the observer. These effects are imperceptible at everyday scales because the speeds at which they become significant are much higher than those we encounter in day-to-day life.
Growth in Biological Systems
In biology, growth in weight and length can indicate a healthy development. For instance, regular measurement of a baby's weight and length during the first year can show if the baby is growing normally or if there might be health concerns. Similarly, during puberty, adolescents undergo a growth spurt in both height and weight, which is influenced by hormonal changes.
It is worth noting that while bathroom scales measure weight, they are calibrated to display mass, factoring in the acceleration due to gravity. Therefore, on the moon, a scale would show a different weight due to the lower gravitational force, but the mass would remain unchanged.