Law of Conservation of Energy
Energy cannot be created or destroyed; it can only be transformed or transferred. In a closed system, total energy is constant.
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Conservation of mechanical energy
In the absence of non-conservative forces (like friction), the total mechanical energy E = KE + PE remains constant. As an object falls, PE decreases and KE increases by the same amount. When friction is present, some mechanical energy is converted to thermal energy, but the total energy of the system (including heat) is still conserved.
✔ Key takeaway: Energy is conserved; it transforms from one form to another.
Link to simulator: Toggle friction and watch total energy and thermal energy.
💭 Think about this:
Where does the energy go when a ball rolls to a stop on a rough surface?