Force analysis is as shown in the figure:
(2) In this process, people and ships are moving in a straight line with uniform speed, and the initial speed is zero.
Assuming that the static friction between man and ship is F, the drag coefficient of ship is K, the acceleration of ship and man is a 1 and a2, and the displacement of ship and man is s 1 and s2, respectively, there are
The ship analysis is as follows: f-k (m1+m2) g = m1a1①.
s 1= 12a 1t2 ②
The human analysis is f=m2a2 ③.
s2= 12a2t2？ ④
S 1+s2=L ⑤。
① ② ③ ④ ⑤ If you substitute the data at the same time, you can get f=290N, A 1 = 0.2m/S2, A2 = 5.8m/S2, s1= 0.4m6.
That is, the displacement of the ship is 0.4m
(3) According to the conservation of energy, at least the work done by people in this process should include the increase of kinetic energy of people and ships and the work done by ships to overcome resistance in this process.
Increase of kinetic energy of man and ship △ ek =12m1(a1t) 2+12m2 (a2t) 2? 0? ⑦
Work done by ship to overcome resistance w1= k (m1+m2) GS1⑧
W=△Ek+W 1 ⑨
⑦ ⑧ W=3480J when substituting data at the same time.
Answer: (1) The manpower is as shown in the figure:
(2) The displacement of the ship is 0.4m；;
(3) People should do at least 3480J of work.