I keep getting “Conservation of mechanical energy” questions wrong in Work, Energy & Power. What's the trap?
applying it when friction or other non-conservative forces are present.
The usual trap: applying it when friction or other non-conservative forces are present. How to avoid it: if there's friction, account for the energy lost as heat. Go back to the definition — when only conservative forces act, KE + PE stays constant.
Key point
Conservation of mechanical energy
Common mistake
applying it when friction or other non-conservative forces are present.
Memory tip
if there's friction, account for the energy lost as heat.
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