Fluidos (parte 5)

Summary

This video explains the concept of fluid pressure and buoyancy. It explores how pressure in a liquid increases with depth and acts in all directions. Using the example of a submerged cube, the script derives the net force acting on the cube due to pressure differences. This leads to the introduction of Archimedes' Principle, which states that the buoyant force acting on an object is equal to the weight of the displaced liquid. The video provides an insightful explanation of why objects float and the relationship between fluid pressure and buoyancy.

Takeaways

• 😀 Pressure in a liquid is affected by depth, and the deeper you go, the higher the pressure at that point.
• 😀 Pressure acts in all directions in a fluid, not just downward, as this keeps the object at rest in a stationary state.
• 😀 The pressure difference between the top and bottom of a submerged object creates a net upward force.
• 😀 When a cube is submerged in liquid, the pressure at the bottom is higher than at the top due to greater depth.
• 😀 The net force on the submerged cube is determined by the difference in pressures at the top and bottom, multiplied by the area.
• 😀 The formula for net force is: F_net = (Pressure_bottom - Pressure_top) * Area.
• 😀 Pressure at the top of a submerged object depends on the density of the liquid, depth of immersion, and gravitational acceleration.
• 😀 Pressure at the bottom of the submerged object depends on the liquid’s density, the depth of immersion plus the object’s dimension.
• 😀 When calculating the net force, the difference in pressures at the top and bottom of the object leads to a buoyant force acting upward.
• 😀 Archimedes' Principle explains that the buoyant force is equal to the weight of the displaced liquid, which explains why objects float.

Q & A

What determines the pressure at a specific point in a liquid?

The pressure at a specific point in a liquid is determined by the depth at which the point is located. The deeper the point, the greater the pressure.

How does pressure act in a liquid at rest?

Pressure in a liquid at rest acts in all directions. This means that at any given point, the pressure is exerted equally upward, downward, and sideways.

Why does pressure act in all directions in a static liquid?

In a static liquid, pressure acts in all directions because a stationary particle experiences no net force. If the pressure were different in any direction, the particle would accelerate, which would contradict the assumption of a stationary system.

What happens to a submerged object if the pressure acting on it is unequal in different directions?

If the pressure acting on a submerged object is unequal in different directions, it will experience an upward or downward force, causing it to move. This difference in pressure is why objects can float or sink.

How does the pressure vary on a submerged cube in a liquid?

The pressure on the submerged cube varies with depth. The pressure at the bottom of the cube is greater than the pressure at the top, as the bottom is deeper in the liquid.

What is the formula for calculating the net force acting on a submerged object?

The net force on a submerged object is calculated by subtracting the force exerted on the top of the object from the force exerted on the bottom. This results in the net upward force, also known as buoyant force.

How does the volume of the submerged object relate to the buoyant force?

The buoyant force on an object is directly related to the volume of the liquid displaced by the object. The greater the volume of the displaced liquid, the greater the buoyant force.

What is Archimedes' Principle?

Archimedes' Principle states that the buoyant force on a submerged object is equal to the weight of the liquid displaced by the object.

How can the buoyant force be calculated?

The buoyant force can be calculated by multiplying the volume of the displaced liquid by the density of the liquid and the acceleration due to gravity. This is equivalent to the weight of the displaced liquid.

What is the relationship between the buoyant force and the weight of the displaced liquid?

The buoyant force is equal to the weight of the liquid displaced by the object. This is why objects float: the buoyant force counteracts the weight of the object.