Based on the Law of Conservation of Energy, the statement that is true is:
Energy cannot be created or destroyed by ordinary chemical or physical means.
The other statements you provided do not accurately represent the Law of Conservation of Energy. Here’s why:
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Kinetic energy is always equal to potential energy: This is not true; the two can vary independently depending on the situation (e.g., a ball thrown upwards has kinetic energy that decreases as potential energy increases).
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Kinetic energy is equal to potential energy minus temperature: This statement is not correct and does not accurately reflect any fundamental principle of physics.
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Potential energy is equal to thermal energy plus kinetic energy: This also is not correct; total energy in a system includes kinetic energy and potential energy, but thermal energy is a different form of energy related to temperature and heat.
So, the most accurate and relevant statement in relation to the Law of Conservation of Energy is the third one: energy cannot be created or destroyed by ordinary chemical or physical means.