Question

Катер отошёл от пристани и двинулся по течению реки.Через 1,5 ч он повернул обратно и двигался против течения такое же время.На каком расстоянии от пристани он оказался,если скорость катера в стоячей воде 21,6км/ч,а скорость течения реки 1,9км/ч?

Answer 1

21,6+1,9=23,5 скорость по течению
21,6-1,9=19,7 скорость против теч
23,5*1,5=35,25км путь по течению
19,7*1,5=29,55 км путь против теч
35,25-29,55=5,7 км

Answer 2

Problem Analysis

The problem describes a scenario where a boat moves downstream for 1.5 hours and then returns upstream for the same amount of time. We are asked to find the distance the boat traveled from the dock. The boat's speed in still water is 21.6 km/h, and the speed of the river's current is 1.9 km/h.

Solution

To solve this problem, we can use the formula: distance = speed × time

Let's calculate the distance the boat traveled from the dock.

Downstream Movement

The boat's speed relative to the water when moving downstream is the sum of its speed in still water and the speed of the current. Therefore, the speed of the boat downstream is: 21.6 km/h + 1.9 km/h = 23.5 km/h

Using the formula, the distance traveled downstream is: distance_downstream = speed_downstream × time distance_downstream = 23.5 km/h × 1.5 h distance_downstream = 35.25 km

Upstream Movement

When moving upstream, the boat's speed relative to the water is the difference between its speed in still water and the speed of the current. Therefore, the speed of the boat upstream is: 21.6 km/h - 1.9 km/h = 19.7 km/h

Using the formula, the distance traveled upstream is: distance_upstream = speed_upstream × time distance_upstream = 19.7 km/h × 1.5 h distance_upstream = 29.55 km

Total Distance Traveled

The total distance traveled by the boat from the dock is the sum of the distances traveled downstream and upstream: total_distance = distance_downstream + distance_upstream total_distance = 35.25 km + 29.55 km total_distance = 64.8 km

Conclusion

The boat was approximately 64.8 kilometers away from the dock after the described movements.

I hope this helps! If you have further questions, feel free to ask.