The distance between quays A and B is 171 km. A motor ship departed from pier A at a speed of 45

| September 17, 2021 | education

The distance between quays A and B is 171 km. A motor ship departed from pier A at a speed of 45 km / h. 12 minutes later another motor ship departed from the pier B towards him, the speed of which was 36 km / h. How many hours after the departure of the first ship will they meet?

First of all, let’s express 12 minutes in hours. We have: 12 minutes = (12: 60) hours = 1/5 hour.
Since the speed of the motor ship that departed from the pier A is 45 km / h, this motor ship in 12 minutes will move away from A at a distance of (1/5 hour) * (45 km / h) = (1/5 * 45) km = (45: 5) km = 9 km.
Then the distance between the two motor ships will be reduced by 9 km and will be equal to 171 km – 9 km = 162 km.
According to the terms of the assignment, the ships move towards each other. Therefore, they approach each other (before meeting) at a speed equal to the sum of the speeds of motor ships, that is, at a speed of 45 km / h + 36 km / h = 81 km / h.
Dividing the distance of 162 km by the speed of 81 km / h, we determine the time required before the meeting after the departure of the second motor ship. We have: (162 km): (81 km / h) = (162: 81) hours = 2 hours.
Let’s add 12 minutes to two hours and answer the task question. The motor ships will meet in 2 hours 12 minutes after the departure of the first motor ship.
Answer: The motor ships will meet in 2 hours 12 minutes after the departure of the first motor ship.



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