The key difference between buoyant force and gravitational force is that gravitational force is the force that pulls down things while buoyant force is the upward force that keeps things afloat in liquids.
Gravitational force and buoyant force are two important forces in nature, which help the statics and dynamics of bodies. These forces play a crucial role in fields such as nautical engineering, astronomy, physics and many more. It is vital to have a clear understanding of both gravitational force and buoyant force in order to excel in such fields. In this article, we are going to discuss what gravitational force and buoyant force are, their definitions, the similarities between these two forces, the applications of these two, as well as the difference between gravitational force and buoyant force.
CONTENTS
1. Overview and Key Difference
2. What is Buoyant Force
3. What is Gravitational Force
4. Side by Side Comparison – Buoyant Force vs Gravitational Force in Tabular Form
5. Summary
What is Buoyant Force?
Buoyancy is the upward force by a fluid on an object. The pressure of a static fluid only depends on the depth of the point the pressure is measured, the gravitational acceleration, and the density of the fluid. Treating the other two as constants the pressure is only dependent on the depth. Deeper the point, higher the pressure will be. This is a linear proportionality. This means any object placed inside a fluid will feel the difference in pressure at the top and the bottom. The bottom pressure, which is higher than the top pressure, will try to push the object upward. This is named the buoyant force.
Since the buoyant force is equal to or higher than the weight of the object, it will not sink. If the weight of the object is higher than the buoyant force, it will sink. Even if the pressure differs with the height, the pressure difference for a specific height difference will be the same throughout the fluid. This means that the buoyant force does not change according to the place of the object in the fluid.
What is Gravitational Force?
Sir Isaac Newton was the first person to formulate gravity. But before him, Johannes Kepler and Galileo Galilei laid out the foundation for him to formulate the concept of gravity. The famous equation F = G M1 M2 / r2 gives the strength of the gravitational force, where M1and M2 are point objects and r is the displacement between the two objects.
Figure 01: Gravitational Force and Buoyant Force
For real-life applications, they can be normal objects of any dimension and r is the displacement between the centers of gravity. The gravitational force is considered as an action at a distance. This gives rise to the problem of the time gap between interactions. This can be omitted using the gravitational field concept. Gravitational force only attracts object. Repulsion in gravitational fields is not present. The gravitational force by the earth on an object is also known as the weight of the object on earth. Gravity is a mutual force. The force from object A on object B is as same as the force from object B on object A.
What is the Difference Between Buoyant Force and Gravitational Force?
Gravitational force is the force that pulls down things while buoyant force is the upward force that keeps things afloat in liquids. This is the key difference between buoyant force and gravitational force. Moreover, gravitational forces act in any medium while buoyant forces are only present in fluids. In addition, buoyant forces involve repulsion between the object and the fluid while gravitational forces involve attraction.
Summary – Buoyant Force vs Gravitational Force
The key difference between buoyant force and gravitational force is that gravitational force is the force that pulls down things while buoyant force is the upward force that keeps things afloat in liquids.
Image Courtesy:
1. “Buoyancy” By Luis Mavier Rodriguez Lopez – done for Wikipedia, might be found at my webpage in the future: (CC BY 2.5) via Commons Wikimedia