𝐄𝐯𝐚𝐥𝐮𝐚𝐭𝐢𝐨𝐧 𝐨𝐟 𝐅𝐨𝐮𝐫 𝐄𝐧𝐞𝐫𝐠𝐲–𝐌𝐨𝐦𝐞𝐧𝐭𝐮𝐦 𝐑𝐞𝐥𝐚𝐭𝐢𝐨𝐧𝐬 .

𝐄𝐯𝐚𝐥𝐮𝐚𝐭𝐢𝐨𝐧 𝐨𝐟 𝐅𝐨𝐮𝐫 𝐄𝐧𝐞𝐫𝐠𝐲–𝐌𝐨𝐦𝐞𝐧𝐭𝐮𝐦 𝐑𝐞𝐥𝐚𝐭𝐢𝐨𝐧𝐬 Energy and momentum are two quantities that arise from the variables of motion such that they are conserved and share the same structure. However, energy is associated with time, whereas momentum is associated with the spatial dimensions. Different formulations unify the definitions of energy and momentum that satisfy this description, depending on the conditions in which a body moves. Accordingly, in each case there exists a relation between energy and momentum. We have a formula for this relation in two well-known cases. We also have a formula for another case that can be inferred from the physics known today. In addition, we now have a proposed formula for general cases that include a varying gravitational field. Our aim is to study these four formulas in terms of their range of validity and their physical significance.