Peoples Physics Book Version-2

http://www.ck12.org Chapter 4. One Dimensional Motion Version 2

means that car A travels 125 (which is 5km) of the distance and car B travels 127 (which is 7km) of the distance. Car
B takes

50km/hr×t=5km⇒t=

5km

50km/hr

⇒t=.1hr=6min

to cover 5km. Car A takes

70km/hr×t=7km⇒t=

7km

70km/hr

⇒t=.1hr=6min

to cover 7km. Therefore the time before the collision is 6 minutes.