Explanation:
The above two versions are contradicting to each other. One says that energy and work are one and the same. The other says that energy and work are different. The conclusion of this contradiction must be given. We say that the work is basically energy but it becomes different due to the association with the instrument. The notable [1] energy becomes un-notable [2] work due to the association with instrument and hence, the work can neither be identified as the notable energy nor as the notable instrument. The process of walking is work. It is different form the instrumental legs and also the causal energy. We can notice only the energy and the legs but the work, which is different from these two, cannot be noticed. The inert heat energy can be noticed by the thermometer directly and the instrumental legs are directly noticed by the two eyes. But the process of walking as invisible work, cannot be noticed directly.
Note:
Suppose the legs are walking. The inert energy in the form of heat, that is present in the legs, and which is working as mechanical energy, can be measured by the thermometer. You are also able to notice the legs by your naked eye. Both energy and instrument are thus notable. But the work, walking, is not notable. You are only seeing the legs moving. You are not measuring work. There is no work-meter. Work is neither the legs nor the heat energy present in the legs, nor the distance traveled. It is only inferred; not perceived. Work is not notable.
Suppose you have walked one mile. You can see the legs. You can also see the amount of energy (in the form of heat) spent by the legs by using a thermometer. You can also measure the distance walked—1 mile. One mile is a unit of distance. Likewise, if 10 calories are spent, that is only heat energy. But the units of work are not noticeable. Then what are the units of work? There are no direct units of work; there are only indirect units in terms of energy. Work is measured indirectly in terms of energy. Hence, work is unnoticed. Work is only inferred; not perceived.
Why is energy called as inert energy?
Inert in this context is not to be understood in terms of whether it is dynamic or static. Inert means, that which cannot know or that which cannot have knowledge. So, inability to know or inability to possess knowledge, is the criterion. Electricity does not have the characteristic of knowledge. Hence, it is inert. Whether it is static or dynamic is irrelevant; whether or not it can possess knowledge is the issue. The process of knowing is not there in electricity, therefore, it is inert.
[1] Tangible
[2] Intangible
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