FirstPrinciplesa Physoly project
EN-05energytrap · Dimensional inconsistency

Power is not the same as energy

  1. 01

    The tempting model

    Using watts and joules interchangeably.

  2. 02

    Why it feels right

    Both describe 'how much work', so they blur together.

  3. 03

    Where it breaks · how to catch it

    A term mixes W and J, or you forgot to multiply power by time.

  4. 04

    The correct model

    Power is the rate of energy transfer, P = E/t (watts = joules per second). Energy = power × time.

  5. 05

    Repair · see it, then test it

    worked example A 60 W bulb runs for 2 hours. Energy used?

    Tempting move

    60 J.

    Correct move

    E = P·t = 60 · 7200 s = 4.32 × 10⁵ J.

    Test the repair EN-05 · transfer
    include J

    Make a fresh prediction before referring to the worked example.

    Then practise it on the ladder

    R20Power as a rateadds: Power is energy per time.