Question

火車從甲站到乙站正常行駛速度是60 km/h,有一次火車從甲站開出,由于遲開了5分鐘,司機把速度提高到72 km/h,才剛好正點到達乙站。求:

(1)甲、乙兩站間的距離;

(2)火車從甲站到乙站正常行駛的時間。

Answer 1

【解析】設(shè)正常行駛時所用時間為t,甲、乙兩站間的距離為s,正常行駛速度v₁=60 km/h=m/s,提高后的速度v₂=72 km/h=20 m/s,則:

v₁t=s                                                                           ①(3分)

v₂(t-60×5)=s　                                                             ②(3分)

將已知數(shù)據(jù)代入①②式解得:

t=1 800 s=0.5 h　                                                               (3分)

s=30 km　                                                                       (3分)

答案:(1)30 km　(2)0.5 h