The point in the immersed body through which the resultant pressure of the liquid may be taken to act is known as ______ ?
Try it first: pick an option, then read the explanation.
Asked in SSC JE 1 March 2017 Morning Shift
Detailed Explanation
When a solid body or surface is immersed in a liquid, hydrostatic pressure acts everywhere perpendicular to its surface. The single point through which the vector resultant of all these distributed pressure forces acts is defined as the centre of pressure.
Definitions of key centres in fluid mechanics:
- Centre of Pressure: The specific point of application on an immersed surface through which the entire resultant hydrostatic pressure force acts.
- Centre of Gravity: The point through which the resultant gravitational force (weight) of the body acts.
- Centre of Buoyancy: The geometric centroid of the displaced liquid volume, through which the upward buoyant force acts.
- Metacentre: The theoretical point of intersection between the vertical line of action of buoyant force (in tilted condition) and the original vertical axis of symmetry.
Why “centre of pressure” Is Correct
By standard physical definition, the point through which the resultant distributed fluid pressure acts on an immersed body is called the centre of pressure.
Why the Other Options Are Wrong
- A. centre of gravity: Centre of gravity is the point of application of the body's own gravitational weight.
- B. centre of buoyancy: Centre of buoyancy is the centroid of the displaced liquid volume through which upward buoyancy acts.
- D. metacentre: Metacentre is the point about which a floating body oscillates when tilted through small angles.
Key Point
Centre of pressure is the point of action of the resultant hydrostatic thrust on an immersed surface.
Key Concepts for Students
- Centre of pressure applies to both plane and curved surfaces.
- On a submerged curved surface, the horizontal and vertical component forces intersect at the centre of pressure.
- Centre of buoyancy applies to the displaced volume; centre of pressure applies to the wetted surface area.
Practice more: this is question 26 in Hydrostatic Pressure MCQs – Part 2. Try the whole set and check every answer instantly.