3. An escalator is used to move 20 people (60 kg each) per minute from the first floor of a department
store to the second floor, 5 m above. The power required is approximately ______.
(A) 100 W
(B) 200 W
(C) 1000 W
(D) 2000 W
(E) 4000 W
詳解 (共 1 筆)
未解鎖
...........=mgh*人數*重...