The strength of the buoyant force depends on the density of the fluid and the volume of the object submerged. When an object is immersed in a fluid, the fluid exerts pressure on all sides of the object. The pressure at the bottom of the object is higher than the pressure at the top due to the weight of the fluid above it. This pressure difference creates a net upward force, which is the buoyant force.
If the density of the fluid is greater than the density of the object, the buoyant force is greater than the weight of the object. As a result, the upward thrust is stronger than the downward force, causing the object to experience a net upward force and float or rise in the fluid.
Conversely, if the density of the object is greater than the density of the fluid, the buoyant force is weaker than the weight of the object. In this case, the downward force is stronger than the upward thrust, causing the object to sink.
- Upthrust, or buoyant force, always acts in the upward direction because it is a result of the pressure difference in a fluid. When an object is immersed in a fluid, the fluid exerts pressure on the object from all sides. This pressure is higher at deeper levels due to the weight of the fluid above.
The pressure difference creates a net force that pushes the object upward. This upward force, known as the buoyant force or upthrust, counteracts the weight of the object. According to Newton's third law of motion, for every action, there is an equal and opposite reaction. The downward force exerted by the object on the fluid is met with an equal and opposite upward force exerted by the fluid on the object.
Therefore, upthrust always acts in the upward direction, opposing the force of gravity and allowing objects to float or rise in a fluid.