Question

Які сили діють на тіло, якщо воно знаходиться в рідині?

Answer 1

На тело, находящееся в жидкости, действует сила тяжести, направленная вертикально вниз,

                 F(т) = mg,

и выталкивающая сила (сила Архимеда)  

                 Fₐ = ρgV,

численно равная весу жидкости в объеме погруженной части тела и направленная вертикально вверх.

Если сила тяжести больше силы Архимеда, то тело тонет.

Если сила тяжести меньше силы Архимеда, то тело плавает на поверхности жидкости (часть тела находится выше уровня жидкости)

Если эти силы равны, то тело находится в покое на любой глубине погружения. В этом случае говорят, что тело обладает нулевой плавучестью.

Answer 2

Forces Acting on an Object in a Fluid

When an object is submerged in a fluid, such as a liquid, several forces act on it. These forces include:

1. Buoyant Force: The buoyant force is the upward force exerted by a fluid on an object submerged in it. It is equal to the weight of the fluid displaced by the object. According to Archimedes' principle, an object immersed in a fluid experiences a buoyant force equal to the weight of the fluid it displaces. This force acts in the opposite direction to gravity and is responsible for the apparent loss of weight of an object in a fluid.

2. Gravity: Gravity is the force that attracts objects towards each other. It acts vertically downwards and is responsible for the weight of the object. The weight of the object is the force exerted by gravity on it and is equal to the mass of the object multiplied by the acceleration due to gravity.

3. Drag Force: When an object moves through a fluid, it experiences a drag force. The drag force opposes the motion of the object and depends on factors such as the shape and size of the object, the speed of the object, and the viscosity of the fluid. The drag force can be further divided into two components: viscous drag and form drag.

- Viscous Drag: Viscous drag is caused by the friction between the fluid and the surface of the object. It depends on the viscosity of the fluid and the relative velocity between the object and the fluid. - Form Drag: Form drag is caused by the pressure difference between the front and back of the object as it moves through the fluid. It depends on the shape and size of the object.

4. Surface Tension: Surface tension is the property of a liquid that causes its surface to behave like a stretched elastic sheet. It is caused by the cohesive forces between the liquid molecules. Surface tension tends to minimize the surface area of a liquid, resulting in phenomena such as capillary action and the formation of droplets.

5. Pressure: When an object is submerged in a fluid, it experiences a pressure difference between different points on its surface. The pressure exerted by a fluid depends on its density and the depth of the object below the surface. The pressure increases with depth and is higher at the bottom of the object compared to the top.

These are some of the main forces that act on an object in a fluid. The specific forces experienced by an object will depend on factors such as the properties of the fluid, the shape and size of the object, and the motion of the object through the fluid.

[[4]](https://core.ac.uk/download/pdf/162894389.pdf)