Mistake Master

Power

Power is not the same as energy. Energy is the amount; power is the rate. Lift a heavy box up the same stairs slowly or quickly, and the energy delivered is the same. The power, on the other hand, is not. Same destination, faster trip, more power per second. A 60 W bulb is not storing 60 W of anything; it is a 60-joules-per-second device. That single distinction, rate vs amount, is where the traps live.

A · IN 2 SECONDS Δt 2.0 s ΔE = mgh ΔE 1600 J P P 800 W P = ΔE / Δt 800 W B · IN 8 SECONDS Δt 8.0 s ΔE = mgh ΔE 1600 J P 200 W P P = ΔE / Δt 200 W
The yellow energy bar is identical in both panels: 1600 J is delivered either way. The pink power bar is what changes. Four times the time, one quarter the power. The dashed outline shows where panel B’s bar would reach if it matched panel A.
PowerLab · Open the sandbox and explore three configurations →

Three traps catch students again and again. The stockpile: treating a watt rating like a stored amount of energy, as if a 60 W bulb has 60 joules sitting inside it. The angle: forgetting the cosine in $P = Fv\cos\theta$, so a sideways shove looks like it still delivers full power. The sign: reading negative power as a smaller power, when the sign is really telling you energy is leaving the system.

The work

3 ways in · any order
Lesson
Power

Five sections: frame power as a rate, define both equation-sheet forms, work a two-route example that resolves to the same number, 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 power: watts treated as stored energy, sign read as size, power read as a vector. 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