Archimedes principle and buoyant force | Fluids | Physics | Khan Academy

TL;DR

Archimedes' principle states that the net upward force or buoyant force on an object submerged in a fluid is equal to the weight of the fluid displaced.

Transcript

Let's say we have a cup of water. Let me draw the cup. This is one side of the cup, this is the bottom of the cup, and this is the other side of the cup. Let me say that it's some liquid. It doesn't have to be water, but some arbitrary liquid. It could be water. That's the surface of it. We've already learned that the pressure at any point within t... Read More

Key Insights

• 🫗 Pressure within a liquid is determined by depth and acts in all directions within a stationary liquid or on a stationary object within the liquid.
• 🧊 The net force on a submerged cube is equal to the difference in pressure between the bottom and top multiplied by the surface area.
• 🏋️ The net force on a submerged object is equal to the weight of the fluid displaced, known as the buoyant force.

Questions & Answers

Q: What determines the pressure within a liquid?

The pressure within a liquid is determined by the depth or how far down we go into the liquid.

Q: Why is pressure acting in all directions within a stationary liquid?

Since the liquid or object within the liquid is stationary, in order to maintain equilibrium, the pressure must act equally in all directions.

Q: How does the pressure change at different points on a submerged cube?

The pressure is higher at deeper points on the submerged cube compared to shallower points.

Q: What is Archimedes' principle?

Archimedes' principle states that the net upward force or buoyant force on an object submerged in a fluid is equal to the weight of the fluid displaced.

Summary & Key Takeaways

• Pressure within a liquid is dependent on depth and acts in all directions.

• The pressure is equal in all directions within a stationary liquid or on a stationary object within the liquid.

• When a cube is submerged in a liquid, the net force acting on it is equal to the weight of the liquid displaced.