A person holds a suitcase while standing motionless at a bus stop for five minutes. Since the suitcase remains at the same position throughout, what is the work done by the person on the suitcase?
Zero
Work done is \(W = Fd\cos\theta\); it needs a displacement of the point of application of the force.
The person applies an upward force equal to the weight of the suitcase, but the suitcase does not move, so d = 0.
Therefore \(W = F \times 0 = 0\). The tiredness felt is due to internal muscle effort (biochemical energy use), not mechanical work on the suitcase.
Negative or positive work would need displacement against or along the force; “equal to the weight” confuses force (newton) with work (joule).
Hence, the answer is Zero.
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