Question

Шарик из пробкового дерева массой 6 г привязан нитью ко дну сосуда, заполненного водой. Половина объёма шарика погружена в воду. Плотность пробкового дерева 0,3 г/см3, плотность воды 1г/см3. Найти силу натяжения нити. Ответ выразить в миллиньютонах [мН]. Ускорение свободного падения принять равным 10 м/с. ПОМОГИТЕ!!! Я Тупой :)

Answer 1

Ответ:

Объяснение:

Дано:

m = 6 г = 6·10⁻³ кг

V₁ = V/2

ρ = 0,3 г/см³ = 300 кг/м³

ρ₁ = 1 г/см³ = 1000 кг/м³

g = 10 м/с²

___________________

T - ?

1)

Вес шарика:

P = m·g = 6·10⁻³·10 = 60·10⁻³  Н

Объем шарика:

V = m / ρ = 6·10⁻³ / 300 = 20·10⁻⁶ м³

2)

Сила Архимеда:

Fₐ = ρ₁·g·V₁ = ρ₁·g·V/2 = 1000·10·20·10⁻⁶ / 2 = 100·10⁻³ Н

3)

Натяжение нити:

T = Fₐ - P = (100 - 60)·10⁻³ = 40·10⁻³  Н         или    Т = 40 мН

Answer 2

Calculation of Tension Force

To find the tension force in the string, we need to consider the forces acting on the cork ball. The forces involved are the buoyant force and the weight of the cork ball.

The buoyant force is equal to the weight of the water displaced by the submerged part of the cork ball. Since half of the volume of the cork ball is submerged in water, the buoyant force can be calculated as follows:

Buoyant force = (density of water) * (volume of submerged part of cork ball) * (acceleration due to gravity)

The weight of the cork ball can be calculated as follows:

Weight of cork ball = (mass of cork ball) * (acceleration due to gravity)

The tension force in the string is equal to the difference between the buoyant force and the weight of the cork ball. Therefore, the tension force can be calculated as follows:

Tension force = Buoyant force - Weight of cork ball

Let's calculate the tension force using the given values:

Given: - Mass of cork ball = 6 g - Density of cork wood = 0.3 g/cm³ - Density of water = 1 g/cm³ - Acceleration due to gravity = 10 m/s²

First, let's convert the mass of the cork ball to kilograms: - Mass of cork ball = 6 g = 0.006 kg

Next, let's calculate the volume of the submerged part of the cork ball: - Volume of submerged part of cork ball = (1/2) * (total volume of cork ball)

The total volume of the cork ball can be calculated using its mass and density: - Total volume of cork ball = (mass of cork ball) / (density of cork wood)

Now, let's calculate the buoyant force: - Buoyant force = (density of water) * (volume of submerged part of cork ball) * (acceleration due to gravity)

Finally, let's calculate the weight of the cork ball and the tension force: - Weight of cork ball = (mass of cork ball) * (acceleration due to gravity) - Tension force = Buoyant force - Weight of cork ball

Let's perform the calculations:

Step 1: Convert the mass of the cork ball to kilograms: - Mass of cork ball = 0.006 kg

Step 2: Calculate the volume of the submerged part of the cork ball: - Total volume of cork ball = (0.006 kg) / (0.3 g/cm³) = 0.02 cm³ - Volume of submerged part of cork ball = (1/2) * (0.02 cm³) = 0.01 cm³

Step 3: Calculate the buoyant force: - Buoyant force = (1 g/cm³) * (0.01 cm³) * (10 m/s²) = 0.1 N

Step 4: Calculate the weight of the cork ball: - Weight of cork ball = (0.006 kg) * (10 m/s²) = 0.06 N

Step 5: Calculate the tension force: - Tension force = Buoyant force - Weight of cork ball = 0.1 N - 0.06 N = 0.04 N

Therefore, the tension force in the string is 0.04 N.

Note: The answer is not expressed in millinewtons (mN), but in newtons (N).