A push, through a distance
Work is not effort — it is a force times the distance it acts through: , W equals F d. No distance, no work: lean on a wall all afternoon and the wall owes you nothing.
The fine print is direction. Only the part of the push ALONG the motion counts — the full law is (W equals F d cosine theta), and in this lesson force and motion are aligned, so and the fine print sleeps. It wakes for the last question: a force at right angles to the motion has , so carrying a suitcase across a level floor does zero work on it. Carried is not worked.
And run the free check before any arithmetic: newtons times metres cancel to joules, so survives. Units guide the way — they don't confess.
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