Mistake Master

Conservation of Energy

Energy is not made or destroyed; it changes form. In a frictionless system, kinetic and gravitational potential trade. With friction, they still trade, and some of the budget leaks into a thermal column. The conservation rule does not change; the bookkeeping does. The traps are small in number, and all of them come from forgetting to write down where the joules went.

A · FRICTIONLESS h 30° m Esys 60 J Ug 24 J K 36 J K and Ug trade only B · WITH FRICTION h 30° m Esys 60 J ΔEth 12 J Ug 24 J K 24 J + thermal column grows
Same block, same instant in the slide. Left, no friction: the K and Ug bars trade. Right, with friction: a thermal column joins the stack, and K is shorter. The dashed total-energy outline is identical in both panels. The ledger always balances.
ConservoLab · Open the sandbox and toggle friction →

Three traps. Substance: students claim friction destroys energy. Procedure: they write $K_i + U_i = K_f + U_f$ even when friction is acting. Representation: their bar chart stops balancing because one of the columns they drew was never an energy at all.

The work

3 ways in · any order
Lesson
Conservation of Energy

Five sections: frame the conservation rule, define mechanical energy and the thermal column, work two side-by-side examples (one without friction, one with), lay out the three pitfalls, then a ten-scenario applet that drills each trap directly.

Skill check · 10 scenarios
Diagnostic
10-item topic check

Ten items. Each wrong choice is a real misconception on conservation: friction destroys, equation reused despite dissipation, bar-chart bookkeeping errors. The diagnostic finds which one you reach for first, then sends you to a targeted drill.

Not started · 10 items · ~15 min
Targeted Practice
Drill a single misconception

Pick one of the failure modes you've missed and grind it on its own. The round is adaptive: two correct in a row clears the misconception and you move on.

Take the diagnostic to identify your misconceptions