Buoyancy

If you put a copper ball in a bucket with water, it will sink and the ball of trees will float. Whether a given object sinks or floats in the fluid is determined by the buoyant force of the object. Buoyancy is essentially caused by the pressure at the top of the object and the downward pressure pushing down on the top of the object and pushing it upwards. Since the pressure at the bottom is always greater than the pressure at the top, each object immersed in the fluid must feel an upward buoyant force. Of course, the object also feels downward force due to gravity. And the difference between the buoyancy object's gravity and buoyancy determines whether the object sinks or floats on the surface. If the weight is greater than the buoyancy, the object will sink. The reverse is also true. This is Archimedes (it is said to be bathing), he realizes that a submerged object always moves up the liquid (the water level in the tub rises as you enter Archimedes). Therefore, he concluded that the buoyancy on the object must be equal to the weight of the fluid moving by the object. If the weight of the object is larger than the weight of the displacing fluid, it will sink and if the weight of the object is smaller than the weight of the displacing fluid it will rise. Furthermore, it is evident that the volume of fluid released is exactly equal to the volume of the submerged part of the object, so the buoyancy and weight difference is determined by the relative density of the object and the fluid. In particular, we came to the principle of Archimide.

This explains why wood and polystyrene foam float on the surface and concrete and steel float on the surface. It also explains why it is possible to make ships even from steel or concrete. Even if the actual density of the material is greater, the effective density of the ship can be lower than the effective density of water, so long as the part of the ship under the water is hollow (ie including air).

Rotational stability depends on the relative line of action relative to the object. The upward buoyant force on the object acts through the center of buoyancy, which is the center of the mass of the displaced fluid volume. The gravity of the object acts through its center of gravity. When the center of gravity is below the center of buoyancy, angular displacement produces "correct torque", so buoyant objects stabilize. The stability of the buoyant object on the ground is more complicated and the stable state can be maintained as long as the center of buoyancy moves to the same side when it is out of the equilibrium position even if the center of gravity is higher than the center of buoyancy I will. The center of gravity moves to provide a positive rising moment. When this happens, it is said that suspended matter has a positive center height.

IgVφ = F j force acts on the buoyancy center of the immersed object. The buoyancy center can be calculated by finding the center of gravity of the displaced fluid (ie, the center of gravity of the part of the underwater object below the surface of the fluid). In addition to gravity load, buoyancy also works. If the object is floating, gravity and buoyancy are equal and opposite. Gravity is (as usual) the center of gravity of the whole object. Aerodynamic lift and resistance Resistance Engineers designing large bridges, buildings, or high speed moving ground vehicles spend a lot of time and effort to manage aerodynamic or hydraulic power. Technicians designing bearings and automotive tires are also extremely concerned about fluid dynamics since hydrodynamic forces cause one surface to float above the other surface, thereby reducing friction to a very low level ing.