Question 3 • 2001310 Earth Science Sem 1 - Reeves
The shelf is 200 cm above the floor, which is 2 m. The work done lifting the box is force × distance = 20 N × 2 m = 40 J. Using P = W/t, the power is 40 J ÷ 5 s = 8 W, so the correct choice is B, 8 W.
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