Two cars start at the same time from the same location and go in the same…
2019
Two cars start at the same time from the same location and go in the same direction. The speed of the first car is 50 km/h and the speed of the second car is 60 km/h. The number of hours it takes for the distance between the two cars to be 20 km is ___.
- A.
1
- B.
2
- C.
3
- D.
6
Attempted by 40 students.
Show answer & explanation
Correct answer: B
Two cars travel in the same direction with speeds 50 km/h and 60 km/h.
Key idea: the distance between them changes at the relative speed (the difference of their speeds).
Relative speed = 60 − 50 = 10 km/h.
Time = distance ÷ relative speed = 20 ÷ 10 = 2 hours.
Answer: 2 hours
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