Question

Доска толщиной 5 см плавает в воде,погрузившись на 70%.Поверх воды разливается слой нефти толщиной 1 см.На сколько будет выступать доска над поверхностью нефти? Решите плз через дано/найти/решение

Answer 1

ДАНО
h-5 см
h(2)-1 cm
h'-70%
найти
h(3)-?
решение 
h=100% 
1%=h/100%
1%=0.05
h'=0.05*70%
h'=3.5cm
h(3)=h-(h'+h(2))
h3=5-4.5=0.5cm 
ответ доска будет выступать на 0.5 см

Answer 2

Problem Analysis

To solve this problem, we can use the principle of buoyancy to determine the height of the board above the oil layer. The buoyant force acting on the board is equal to the weight of the oil displaced by the board. We can use this principle to calculate the height of the board above the oil layer.

Given

- Thickness of the board (t): 5 cm - Submersion of the board in water: 70% - Thickness of the oil layer (h): 1 cm

To Find

The height of the board above the surface of the oil layer.

Solution

1. Calculate the submerged height of the board in water. 2. Calculate the volume of water displaced by the submerged portion of the board. 3. Use the volume of water displaced to find the height of the board above the oil layer.

Calculation

1. Submerged Height of the Board in Water: - Submerged height = 70% of board thickness - Submerged height = 0.70 * 5 cm - Submerged height = 3.5 cm

2. Volume of Water Displaced by the Submerged Portion of the Board: - Volume = Area * Height - Area = Area of the board in contact with water - Area = Length * Width - Assuming the board is rectangular, let's assume the width is much larger than the thickness, so the width can be neglected. - Volume = Area * Submerged height - Volume = t * Submerged height - Volume = 5 cm * 3.5 cm - Volume = 17.5 cm^3

3. Height of the Board Above the Surface of the Oil Layer: - The volume of water displaced by the submerged portion of the board will be equal to the volume of the board above the oil layer. - Height of the board above the oil layer = Volume / Area - Height of the board above the oil layer = 17.5 cm^3 / 5 cm - Height of the board above the oil layer = 3.5 cm

Answer

The board will protrude 3.5 cm above the surface of the oil layer.