At this time, the goods drift downstream by 7* 1=7 km.
When finding the lost goods, the distance between the clothes and the goods is 28-7=2 1 km.
They move in opposite directions, which is equivalent to the encounter problem of 2 1/(35+7)=0.5 hours.
It takes 0.5 hours to catch the goods.
The distance between catching up and finding the lost goods, that is, the distance the ship traveled when it returned to catch up with the goods, that is, 35 * 0.5 = 17.5km.
When catching up with the goods, the distance from falling into the water is the total distance of the goods drifting 7 * (1+0.5) = 10.5km, 1, assuming that it takes x hours to catch up.
7x+28+7=35x
X=35/28=5/4 hours
Distance is 35× 5/4 =175/4km.
I hope it's right. 2. Delivery time: (28+7)/(35-7)= 1.25 hours.
The catching-up time is 7 * (1+1.25) =15.75km, 2,1. Before the ship turned around, the relative speed of the ship and cargo was 28+7 = 35 km/h.
2. When finding the lost goods, the distance between them is 35km/h* 1h=35km.
3. The relative speed between them is 35 km/h after U-turn.
4. Time required to catch up with the goods: 35km/(35km/h) =1h.
5. The total time from the loss of goods to the catch-up of goods: 1h+ 1h=2h.
Within 6.2h, the distance of goods drifting with water: 7km/h*2h= 14km.
Therefore: ... 2. When the cargo is found to have fallen, the distance between the ship and the cargo is 28+7=35 (km).
It takes 35/(35-7) = 35/28 = 5/4 =1.25 (hour), 2, which are both downstream and countercurrent. The current speed should be 1, assuming it takes x hours to catch up with the goods.
x=(28+7)/35+ 7x/35
x= 1+7x/35
35x=35+7x
28x=35
x= 1.25
2)35 * 1.25 = 43.75km until the goods are found missing.
3) Cargo chasing 35 * 1 .25-28 =15.75km,1,bookmark, 0, when the cargo ship turns around to chase the cargo, the distance is 35km, and the relative speed between the cargo ship and the cargo is 35-7 = 28km/h.
So the formula calculation is 35/(35-7) =1.25h.
Therefore, the lost distance can be calculated as1.25 * 35-28 =15.75km, 0, and the required time is x,
The distance between the ship and the cargo is 28* 1+7* 1=35 one hour after the cargo is lost.
During this period, the displacement of cargo is 7x, and that of ship is 35x, so x= 1.25 is obtained from 35x-7x=35.
The displacement is 7x (1+1.25) =15.75,0. I want to ask a math application problem in the first volume of the fourth grade of primary school. The content of the question is as follows:
A boat was retrograde along the river at a speed of 28 kilometers per hour. When the ship reached a certain place, it dropped a box of goods and went down the river at a speed of 7 kilometers per hour. The ship sailed for an hour, only to find that a box of goods was missing. At this time, the cargo ship turned around and chased the goods at a speed of 35 kilometers per hour. How long did it take to catch up with the goods? How many kilometers did it take from the time you caught the goods to the time you found them missing?
Necessary formula calculation
The last question is, how far is it from the water when you catch up with the goods?