A straight road connects points and Car travels from to and Car travels from to , both leaving at the same time. After meeting each other, they take minutes and minutes, respectively, to complete their journeys. If Car travels at the speed of , then the speed of Car in km/hr, is
A straight road connects points and Car travels from to and Car travels from to , both leaving at the same time. After meeting each other, they take minutes and minutes, respectively, to complete their journeys. If Car travels at the speed of , then the speed of Car in km/hr, is
Solution
Looking at this problem, I need to find Car 2's speed when two cars meet on a road and then take different times to finish their journeys.
Let me set up what we know:
- Car 1: goes at km/hr, takes min after meeting to reach
- Car 2: goes at unknown speed, takes min after meeting to reach
- Both cars start at the same time
Key insight: When the cars meet, they've been traveling for the same amount of time!
Let me call the meeting point , and let time (in hours) from start until they meet.
At the meeting point :
- Car 1 has traveled: km (distance )
- Car 2 has traveled: km (distance ), where is Car 2's speed
After meeting:
- Car 1 takes min hr to go from to
So distance km
- Car 2 takes min hr to go from to
So distance km
The crucial connection:
- Distance (what Car 1 already traveled) Distance (what Car 2 needs to travel)
- Distance (what Car 2 already traveled) Distance (what Car 1 needs to travel)
This gives us:
... (equation 1)
... (equation 2)
From equation 2:
Substituting into equation 1:
Therefore, Car 2's speed is km/hr.