Question

От пристани одновременно и в одном направлении отправились теплоход и катер. Скорость теплохода-24км/ч , скорость катера -15км/ч. Через 3 часа после отправления теплоход сел на мель.Через некоторое время с помощью буксира теплоход сняли с мели, и через 7 часов он догнал катер. Сколько времени теплоход стоял на мели?

Answer 1

1) 24х3=72 (км) прошел теплоход до того как сел на мель

 

2) 24х7=168(км) прошел теплоход от места где сел на мель до момента когда догнал катер

 

3) 72+168=240(км) прошел теплоход за все время

 

4) 240:15=16(ч) время в пути катера (от начала пути до встречи с теплоходом)

 

5) 16 - (7+3) = 6 (ч) теплоход стоял на мели

 

 

:) Удачи

Answer 2

Problem Analysis

We are given that a ship and a motorboat left the pier simultaneously and in the same direction. The ship's speed is 24 km/h, and the motorboat's speed is 15 km/h. After 3 hours, the ship ran aground. After some time, the ship was towed off the ground, and after 7 hours, it caught up with the motorboat. We need to find out how long the ship was grounded.

Solution

To solve this problem, we can use the concept of relative speed. The relative speed between the ship and the motorboat is the difference between their speeds.

Let's assume that the time the ship was grounded is 't' hours.

When the ship was grounded, the motorboat continued to move at its speed of 15 km/h for 't' hours. During this time, the ship was stationary.

After the ship was towed off the ground, it started moving again and caught up with the motorboat after 7 hours. During these 7 hours, the motorboat also continued to move at its speed of 15 km/h.

Since the ship caught up with the motorboat, the distance covered by both the ship and the motorboat during these 7 hours must be the same.

Let's calculate the distance covered by the motorboat during these 7 hours: Distance covered by the motorboat = Speed of the motorboat * Time = 15 km/h * 7 hours = 105 km

Now, let's calculate the distance covered by the ship during these 7 hours: Distance covered by the ship = Speed of the ship * Time = 24 km/h * 7 hours = 168 km

Since the ship was stationary for 't' hours before catching up with the motorboat, the distance covered by the ship during these 't' hours is 0 km.

Therefore, the total distance covered by the ship is the sum of the distance covered before it was grounded (24 km/h * 3 hours) and the distance covered after it was towed off the ground (168 km): Total distance covered by the ship = (24 km/h * 3 hours) + 168 km = 72 km + 168 km = 240 km

Since the distance covered by the ship is equal to the distance covered by the motorboat, we can set up the following equation: Distance covered by the ship = Distance covered by the motorboat 240 km = 105 km + 15 km/h * t hours

Simplifying the equation: 240 km = 105 km + 15t 135 km = 15t t = 9 hours

Therefore, the ship was grounded for 9 hours.

Answer

The ship was grounded for 9 hours.