1, a boat went down the river for 24 kilometers to reach its destination, and then sailed back to the starting point against the current. The sailing time is planned to be 3 hours and 20 minutes. It is known that the current speed is 3 kilometers per hour. What is the speed of the boat in still water? What is the sailing time of the boat downstream?
2. The speedboat and the raft set off from Pier A at the same time and went down the river. It takes 14 hours for the speedboat to return to a place after 96 kilometers. If it is known that the speedboat meets the raft at a distance of 24 kilometers from A on the way back, find the speed and current speed of the speedboat in still water.
3. It takes 6 hours for the boat to travel downstream from Port A to Port B, and 8 hours to travel upstream from Port B to Port A. One day, when the boat set off from Port A at 6 am and traveled downstream to Port B, it found a survival circle falling into the water on the way, and immediately returned, and found the survival circle one hour later.
(1) How many hours does it take for a ship to drift from Port A to Port B at the current speed?
(2) When did the survival circle fall into the water?
4, 1998, flood fighting and emergency rescue in Hubei, a certain department was ordered to send platoon A to Gongan County, 90 kilometers away from the station. 1.45 minutes later, due to the aggravation of the danger, Company B was sent for support. It is known that company B is 28km faster than platoon A every hour, and just catches up with platoon A at the whole journey 1/3.
(1) Find the speed of company B and the time to catch up with platoon A. 。
(2) When Company B caught up with Company A, the superior ordered Company A to go to Shishou City, which is 24 kilometers away from here, to perform an emergency task, and asked Company A and Company B to arrive at their respective designated places at the same time, trying to find out how many kilometers Company A should accelerate every hour.
Someone swam upstream of the Yangtze River and lost a kettle in one place. He swam forward for another 20 minutes, only to find that he had lost his kettle and immediately returned to catch up. How many minutes did it take him to return to chase after he chased it 2 kilometers away from a place? (Constant return speed)
6. A ship sailed downstream from Port A to Port B, and immediately returned to Port A from Port B after arriving at Port B, which took 8 hours. As we all know, the ship travels 20 kilometers per hour more than in the current, and the ship travels 60 kilometers more than in the last four hours in the first four hours. How many kilometers is it between Port A and Port B?
7. An oil tanker, traveling against the current, with a speed of 12km, can reach Port B in 7 hours. It takes 6 hours to return from port B. What is the speed of the ship in still water and what is its current speed?
8. The speed of the ship in still water is 15km, and the speed of the river is 5 km/h.. It takes six hours for the ship to go back and forth between Port A and Port B. How many kilometers is the voyage between Port A and Port B?
9. A ship sailed from A to B, sailing against the current, with a speed of 24 kilometers per hour. After arriving at B, return to A from B and arrive at 2. Five hours earlier than sailing against the current. As we all know, the speed of water flow is 3 kilometers per hour. What's the distance between a and b?
10, a passenger ship with a speed of 30 kilometers per hour, sailing in the river 165 kilometers, with a water speed of 3 kilometers per hour. Q: How many hours does this passenger ship need to sail?
Catch up with the problem
The distance between Party A and Party B is 420 kilometers, and Party A's bus and Party B's truck meet for 6 hours at the same time. If two cars leave in the same direction from two places, with the truck in front and the bus behind, it will take 10 hours to catch up with the truck, and find the respective speeds of the bus and the truck.
The railway between city A and city B is 240 kilometers long. The express train leaves from city A, and the local train leaves from city B at the same time. See you in three hours. If two cars start from two cities in the same direction, the local train is in front and the express train is behind, 15 hours will catch the local train. How many kilometers do the express train and the local train travel per hour?
As shown in the figure, small robots A and B start from A at the same time, walk backwards, move on a circle with an integer meter diameter, and meet 7 times in 15 minutes: if the speed of A increases by 6 meters per minute, A and B meet 9 times in 15 minutes. What is the maximum circumferential diameter? (∏ take 3. 14)